Close look at iron-based superconductor advances theory

Feb 21, 2013 by Bill Steele
Close look at iron-based superconductor advances theory
Scanning tunneling microscope image of a 48-nanometer square sample of an iron-based superconductor finds a\n array of dumbbell-shaped "impurities" in the electronic structure, like the sample in the inset, confirming a theoretical prediction. The electronic impurities are associated with cobalt atoms (red cross in the inset). Credit: Davis Lab

(Phys.org)—Cornell researchers have resolved a longstanding theoretical debate about the electronic structure of iron-based superconductors by directly observing it at the atomic scale. The work is reported in the Feb. 24 online edition of the journal Nature Physics.

A team led by J. C. Séamus Davis, the James Gilbert White Distinguished Professor in the Physical Sciences and director of the Center for Emergent at Brookhaven National Laboratory, studied a compound of iron, calcium and arsenic that is "doped" by replacing a few of the with cobalt atoms. With around 8 percent doping the material becomes a superconductor. Somehow the cobalt atoms change the environment within this material in a way that allows some electrons to join into "" that then move without resistance.

Surprisingly, however, when the material is "underdoped" with not quite enough cobalt to create superconductivity, an ordinary electric current moves easily along only one axis of the crystal—call it "lengthwise"—but encounters high resistance moving crosswise. This effect increases with the amount of cobalt doping, and may offer a clue to how superconductivity works.

(STM) images of the electronic structure of the material in this underdoped state reveal an array of tiny, elongated groups of electrons in an unusual , aligned with the long axis of the crystal, that act as barriers to electrons moving crosswise. It's like having a lot of long, narrow islands in the ocean, all lined up the same way: Boats moving parallel to the islands can slide through between them, but boats going across are blocked and have to detour. The researchers call these structures "impurities" because they differ from the rest of the electronic structure.

"There has been an assumption that the cobalt dopant atoms are neutral," Davis said. "That assumption is wrong. We showed in this project that the dopant atoms do other very surprising things."

Superconductivity was first discovered in metals cooled almost to absolute zero (-273 degrees Celsius), but recently two families of composite materials based on copper and iron have been discovered that superconduct at temperatures as "high" as 135 degrees above absolute zero, offering the tantalizing promise of creating room-temperature superconductivity, with revolutionary consequences for power generation and transport.

In the basement of the Physical Sciences Building on Cornell's Ithaca campus, Davis and his research team have built an STM resting on massive pillars of concrete, so well insulated from vibration that it can scan a tiny probe across a surface in steps smaller than the width of an atom. By measuring current flow between the probe and the surface researchers can determine the energy states of electrons, in effect measuring how much energy it takes to pull an electron loose from its atom. Other measurements can visualize the effects generated when two interact, as when they are scattered by the newly discovered barriers.

This is the first time the impurity scattering associated with dopant atoms, predicted by some theorists but discounted by others, has been observed experimentally, Davis noted. The observations show increasing numbers of the impurities with increased numbers of cobalt atoms, explaining why the one-way resistance increases with cobalt doping, and confirming that the are responsible, the researchers said. They also said there was strong evidence that magnetism may have something to do with the formation of the impurities—an intriguing idea, since magnetic fields have been shown to interfere with superconductivity.

The next step, Davis said, is to repeat the experiment with other iron-based to verify that the phenomenon is universal, and then for materials scientists to try changing the locations of the dopant atoms to see how this changes the .

Explore further: Finding the 'heart' of an obstacle to superconductivity

Related Stories

Silver sheds light on superconductor secrets

Dec 20, 2012

(Phys.org)—By doping a bismuth-based layered material with silver, Chinese scientists demonstrated that superconductivity is intrinsic to the new material rather than stemming from its impurities.

Recommended for you

IHEP in China has ambitions for Higgs factory

8 hours ago

Who will lay claim to having the world's largest particle smasher?. Could China become the collider capital of the world? Questions tease answers, following a news story in Nature on Tuesday. Proposals for ...

The physics of lead guitar playing

9 hours ago

String bends, tapping, vibrato and whammy bars are all techniques that add to the distinctiveness of a lead guitarist's sound, whether it's Clapton, Hendrix, or BB King.

The birth of topological spintronics

10 hours ago

The discovery of a new material combination that could lead to a more efficient approach to computer memory and logic will be described in the journal Nature on July 24, 2014. The research, led by Penn S ...

The electric slide dance of DNA knots

13 hours ago

DNA has the nasty habit of getting tangled and forming knots. Scientists study these knots to understand their function and learn how to disentangle them (e.g. useful for gene sequencing techniques). Cristian ...

User comments : 71

Adjust slider to filter visible comments by rank

Display comments: newest first

johanfprins
1.5 / 5 (8) Feb 21, 2013
The introduction of the cobalt atoms introduce donor states WITHIN the crystallographic layers (CL's): The donated electrons are available as charge-carriers within the CL's, and they form lower-energy stationary MOTT-type electronic states BETWEEN the CL's.

At "normal-conducting" temperatures conduction occurs within the CL layers, but not with the same ease across them. When increasing the donors associated with the cobalt atoms more electrons are available for conduction along the CL interfaces.

When you decrease the temperature, the MOTT-type orbitals between the CL's increase in density. When their density becomes high enough they can start conducting by thermal hopping: In the literature it is stated that a "pseudogap" has formed. When their density becomes even higher to reach a critical value superconduction occurs by means of hopping assisted by quantum fluctuations (tunneling).

See: http://www.cathod...nism.pdf

No Cooper pairs required!!!!


VendicarE
1 / 5 (5) Feb 21, 2013
Yes of course. This is why all metals are superconductors at room temperature.

"No Cooper pairs required!!!!" - Johanfprins
ValeriaT
1 / 5 (11) Feb 21, 2013
Why the hell nobody of mainstream physics doesn't care about theory, which actually works? The same ignorant situation like with cold fusion, magnetic motors, EMDrive, etc.. just copied through black carbon paper. Incompetent people in mainstream research will never admit, they're really incompetent.
johanfprins
3 / 5 (6) Feb 21, 2013
Yes of course. This is why all metals are superconductors at room temperature.


Really! Why would this be so! Can you explain to me how you got to this stupid conclusion: Or shall we just agree that you are an idiot when it cones to physics!

johanfprins
3.2 / 5 (9) Feb 21, 2013
Why the hell nobody of mainstream physics doesn't care http://www.superc...212.htm?


This "model" (if you can call it one) does not work because it is not predictive. You cannot give the critical condition at which superconduction must occur and also not the reason why at this critical condition it must occur. Thus, this model is no better than the BCS model: Both are just plain nonsense!

Incompetent people in mainstream research will never admit, they're really incompetent.


And you make it easier for them by posting an even more insane, incompetent model than theirs! By pointing you out as the crackpot you are, they are able to claim that ALL people who disagree with them are crackpots; even though they themselves are also crackpots!
Tausch
2.3 / 5 (6) Feb 21, 2013

Q.
Light of a laser is directed at the black rod.
What happens?
johanfprins
1 / 5 (4) Feb 21, 2013

Q.
Light of a laser is directed at the black rod.
What happens?


What black rod are you talking about? There is no mention of this in the above report.
ValeriaT
1 / 5 (8) Feb 21, 2013
This "model" (if you can call it one) does not work because it is not predictive.
It's predictive enough for to increase the temperature of superconductivity onset each year. With compare to you (who did find the diamond superconductivity accidentally) Eck prepares his samples in straightforward systematical way. You apparently didn't realize, that to have some theory still doesn't mean, you've clue how to prepare the optimal superconductor according it. It's analogous to organic chemist, who has some theory of cancer curing, but he doesn't know, which structure the optimal drug should have. And even if he has such a clue, he doesn't know, how to prepare such drug. Which is exactly the situation of yours.
Tausch
2 / 5 (4) Feb 21, 2013
What black rod are you talking about? There is no mention of this in the above report. - J

Your experiment. Your report.
johanfprins
2 / 5 (4) Feb 21, 2013
What black rod are you talking about? There is no mention of this in the above report. - J

Your experiment. Your report.


Most people reading this thread will not have a clue what you are talking about since it does not follow from the report above. It will help if you can give a reason why you have brought up my experiment which proved superconduction at room temperature.

For those people who do not know, Tausch is referring to http://www.cathod...tion.pdf

Now all we need to know is why Tausch brought this up on this thread and ran away from the threads that are relevant to my experiment.

But to answer his/her question: I did not have a laser which I could direct at the "black rod", and has thus not done such an experiment.
ValeriaT
1 / 5 (3) Feb 21, 2013
Tausch: If you don't know the name J.F.Prins and its significance for high temperature superconductivity, you're unqualified for judging of his articles anyway. It's like to ask for Einstein's article in general relativity discussion.
Tausch
1 / 5 (4) Feb 21, 2013
If that is your assumption, then there is no need for a reply from me to either of you. Case closed.
johanfprins
1.8 / 5 (5) Feb 21, 2013
Tausch: If you don't know the name J.F.Prins and its significance for high temperature superconductivity, you're unqualified for judging of his articles anyway. It's like to ask for Einstein's article in general relativity discussion.


I am flattered: If only you would let go of your ducks and foam, we might make a formidable team!
rubberman
1 / 5 (5) Feb 21, 2013
Wow...that is the nicest you two have ever been to each other. Personally Val, I like the ducks (I know you're using it metaphorically) and the "foam" is the word I would use to descibe EM structures as they exist in space. Reading the difference between Cooper pairs and Mott orbitals, I'll go with the orbitals as well.
Antoweif
1 / 5 (3) Feb 22, 2013
You've got to wonder what else kind of technology Johan F. Prins is holding back on us. Surely it isn't just superconducting materials?

He has a answer for everything, but no one seems to be able to prove him wrong in a 'correct' way.
I just don't understand how he could fail to explain quantum entanglement. It didn't make any sense, but I guess a man can't know everything.

Keep up your work though. It's interesting to read!
johanfprins
2.6 / 5 (5) Feb 22, 2013
I just don't understand how he could fail to explain quantum entanglement. It didn't make any sense, but I guess a man can't know everything.


I thought I explained it well. But the words I have chosed might not be clear to someone else: So let me try again:

1. Two wave-entities (or if you want to call them by the misnomer "particles") are not entangled when they are separate entities.

2. They entangle when they form a single wave-entity by losing their separate existences. In text books it is stated that they "are identical and thus indistinguishable". The latter is IMO a misunderstanding of what indistinguishable entails when two or more electrons entangle to form a "multi-electron" wave. They become indistinguishable NOT because they are identical, but because they lose their separate existences to form a holistic wave which is more than the parts from which it formed. It is thus misleading to call such a wave a "multi-electron" wave. It is more than that.

johanfprins
2.3 / 5 (6) Feb 22, 2013
3. A single holistic wave can form parts each of which is not a separate wave-entity: They are still part of a single holistic wave. Thus when Zeilinger et al claim that they send two separate photons along two different paths, these tow parts of the holistic wave are NOT separate photons, until a measurement is made which disentangle them to become two separate photons. Since just before disentanglement the two parts were not separate photons, the polarization of the two photon waves which are formed by disentanglement must correlate.

4. A single photon-wave cannot be split up in smaller separate waves with less energy: but it is "self-entangled" and can therefore split in two parts of the single holistic photon-wave when the photon-wave moves through two slits; and these two parts can then interfere to forma diffracted photon-wave.

5. If before they interfere, you measure through which slit the photon has moved, the two parts cannot disentangle (continued)
johanfprins
2.3 / 5 (6) Feb 22, 2013
5. (continued) The two parts cannot disentangle since a photon cannot be subdivided into separate waves with less energy than that of the photon. The so-called "which-way" measurement must thus collapse the photon to be detected as a single entity by one of the two detectors trained on the slits. It is then incorrectly concluded that the photon has only moved through the slit at which it is being detected. That this is NOT what happens is shown by the fact that such a measurement destroys the diffraction pattern: If this measurement is not made, the two self-entangled parts of the photon interferes to generate a diffracted single photon wave; which when reaching the screen is detected as a single entity by one of the atomic detectors within the screen, at which the diffracted photon-wave collapses. Thus the diffracted photon-wave morphs and disappears as a spot.

q]Keep up your work though. It's interesting to read!

Thank you!
johanfprins
2.3 / 5 (6) Feb 22, 2013
Reading the difference between Cooper pairs and Mott orbitals, I'll go with the orbitals as well.
Why not both? Why both if you do not need Cooper pairs and, as had been pointed out correctly by Bardeen: Cooper pairs cannot tunnel as entities.
For example the SQUID theory favors the Cooper pair mechanism significantly. No it does not: I treat this in my book: See http://www.cathod...ooks.asp and read: "Tunnelling"-junctions and superconduction: NO PHASE SLIP! NO COOPER PAIRS!

Analogy of Cooper pairs exists in superfluids, nucleons at the surface of atom nuclei, etc.
I disagree with this completely. But let us just stick to superconduction where the charge-carriers are pseodo-particles which do not need to be bosons. Why must they be bosons? There is no need for it whatsoever!!

There is not sharp boundary between low temperature and high temperature superconductors of I. and II. type.
The same mechanism, without CP's, is responsible for all SC.
Shootist
2.3 / 5 (6) Feb 22, 2013
Why the hell nobody of mainstream physics doesn't care http://www.superc...212.htm? The same ignorant situation like with cold fusion, magnetic motors, EMDrive, etc.. just copied through black carbon paper. Incompetent people in mainstream research will never admit, they're really incompetent.


The internetz™ is full of insane and mentally unstable individuals.
johanfprins
1 / 5 (4) Feb 22, 2013
I explained already many times, what the particle duality and entanglement is all about.
And your explanations have been wrong all along. There is no such thing as "wave-particle duality"; just as there is no animal that is a a "cat-dog duality".

Prof. Prins models electron with stationary wave, the boundary conditions of which are given/restricted with curvature of space-time. Well, and the particle character is just in this curvature of space-time.


I see you state "particle character" without defining it: therefore it is useless. If you want to call a stationary EM-wave a "particle" you are just confusing the issue. It is still a wave. In fact an electron is simultaneously stationary within one of the multitude of possible inertial reference frames, while moving as coherent EM-waves with different frequencies within all the other inertial reference frames. So which inertial reference frame constitutes your foam if your "electron-particle" is your duck?
johanfprins
1 / 5 (4) Feb 22, 2013
From strict perspective, the quasiparticles transferring charge within superconductors are anyons.


Anyons are fogments (note the o in the place of i) of Frank Wilczek's hallucinating mind.

They don't move with speed of light, so they're not boson.
Why can they only have integral spin when they are moving with the speed of light? A covalent-bond is clearly a boson which is stationary within the molecule it is bonding!

But they can never stay at rest,


I have just now shown they can be at rest.

so they're fermions neither.


Why are they not fermions? What has this to do with staying at rest? a pseudo-electron which is situated at a donor site is clearly a stationary fermion: It is a MOTT-orbital.

They're particle-wave mixture of both states, i.e. the anyons.
Nonsense!
johanfprins
1 / 5 (3) Feb 22, 2013
Look, I'm proponent of dense aether model,
And every time I ask relevant questions about your "aether" you refuse to answer not to incriminate yourself!
so that prof. Frank Wilczek is completely irrelevant to me - but I've no reason to deny the relevance of this concept:
It does not go about Frank Wilczek per se, but about his silly concept of anyons!
I can explain it with my theory and integrate into it.
You cannot even explain your theory on its own!

pseudo-electron which is situated at a donor site is clearly a stationary fermion: It is a MOTT-orbital.
We have been here before and as I have pointed out then, you do not know your physics. There are numerous books about hopping conduction by stationary localized states: Mott and Anderson received a Nobel Prize for their contributions in this field: Did you know this? So you are wrong when you state: "It couldn't transfer electric current after then". YES or NO! Answer before I proceed further
ValeriaT
1.3 / 5 (4) Feb 22, 2013
There are numerous books about hopping conduction by stationary localized states
If something does hops (i.e. the jumps from place to place), then it cannot be stationary anymore - isn't it true? YES or NO!

Your talent regarding twisting of well established concepts is incredible.
johanfprins
1 / 5 (3) Feb 22, 2013
There are numerous books about hopping conduction by stationary localized states
If something does hops (i.e. the jumps from place to place), then it cannot be stationary anymore - isn't it true? YES or NO!


It is stationary when it does not need to hop. That means that if you do not inject a current that has to be transported, very few, if any hops occur.

Your talent regarding twisting of well established concepts is incredible.


Where did I twist what? Please be more specific or acknowledge that your knowledge of physics is regrettably poor. So answer my question:

Do you agree that normally stationary MOTT-orbitals, when a current is NOT injected, can convey an injected current through a material by means of hopping conduction WHEN A CURRENT IS INJECTED TO MOVE FROM ONE CONTACT TO ANOTHER? YES or NO?

Will be back tomorrow!
ValeriaT
1 / 5 (3) Feb 22, 2013
normally stationary MOTT-orbitals, when a current is NOT injected, can convey an injected current through a material by means of hopping conduction
Why not, but the hoping cannot be the mechanism of superconductivity, after then. The hoping is highly irregular motion of charge, which would be connected with radiation of energy and ohmic loses. The Mott insulators do conduct with hopping mechanism regularly, but they exhibit high resistance during this. Mott barrier diodes are based on this effect.
verkle
2 / 5 (4) Feb 22, 2013
I have a feeling that today's comment section is being run over by rats. Sorry, I don't mean to call people rats, but using it only as an allegory.

johanfprins
1 / 5 (2) Feb 23, 2013
.. MOTT-orbitals, .. can convey an injected current through a material by means of hopping conduction

Why not,

AT LAST an admission that you were wrong to state:
It couldn't transfer electric current after then.

but the hoping cannot be the mechanism of superconductivity, after then.

Wrong AGAIN!
The hoping is highly irregular motion of charge,..... The Mott insulators do conduct, but they exhibit high resistance during this.

Correct when it is thermal-hopping; but it is not so when the energy for hopping is supplied by quantum fluctuations: i.e. by a hop which is wrongly called in the standard literature "tunneling". In this case each charge-carrier "borrows" energy (supplied by a quantum fluctuation) to hop, and then returns the energy from where it came. According to the 2nd law of TD, this is the ONLY WAY in which work can be done (to hop) without dissipating energy: Therefore there is no resistance to the motion of the charge-carriers.
johanfprins
1 / 5 (3) Feb 23, 2013
@ValeriT, Natello AKAK!
I repeat my statement and question above:
I see you state "particle character" without defining it: therefore it is useless. If you want to call a stationary EM-wave a "particle" you are just confusing the issue. It is still a wave. In fact an electron is simultaneously stationary within one of the multitude of possible inertial reference frames, while moving as coherent EM-waves with different frequencies within all the other inertial reference frames. So which inertial reference frame constitutes your foam if your "electron-particle" is your duck?


How about a straight answer or are you again going to keep quiet in order not to incriminate your silly model?

ValeriaT
1 / 5 (4) Feb 23, 2013
I have a feeling that today's comment section is being run over by rats.
This is just a beginning. When the layman people will realize, that the ignorance of mainstream science is responsible for contemporary energetic and environmental crisis, we can face the opposite extreme of ignorant antiscientism. The target is not to ruin the science and its research bases, but to understand, on which principles they actually run for to avoid their mistakes in future.
Correct when it is thermal-hopping; but it is not so when the energy for hopping is supplied by quantum fluctuations
Sorry, but the stationary fermions cannot be subject of tunneling or hoping - at the moment, when they're doing such a things, they're normal movable fermions. The absence of jumps is required with non-dispersive character of superconductivity - after then the motion of charge carriers must be actually quite smooth instead. If it wouldn't, it would emanate EM waves, which would lead into energy dissipation
johanfprins
1 / 5 (3) Feb 23, 2013
Sorry, but the stationary fermions cannot be subject of tunneling or hoping - at the moment,
The model has been explained and mathematically modeled in detail: See http://www.cathod...nism.pdf and also the preceding chapters in my book.

The Mott-states are stationary until a charge-carrier is injected. This charge-carrier can only become part of the Mott-orbital array, if it replaces a Mott-orbital near the injection contact. To make way for the injected charge-carriers this MOTT-orbital quantum-hops to the site of the next MOTT-orbital, which makes place by quantum hopping to the nest orbital etc. Thus they ONLY move when charge-carriers are injected, and not even all of them need to move simultaneously; but only enough to pass the current. If the injected current is so large that more MOTT orbitals are required than are available, superconduction stops. This is why a superconductor has an upper limit to the current it can pass through it.
johanfprins
1 / 5 (3) Feb 23, 2013
when they're doing such a things, they're normal movable fermions.

Normal "moveable fermions" are wave-packets which are formed by the applied electric-field within an energy-band when the Fermi-level is situated within the band. These charge-carriers are not there when there is not an applied electric field, since the valence-electrons are then STATIONARY extended waves.

The absence of jumps is required with non-dispersive character of superconductivity - after then the motion of charge carriers must be actually quite smooth instead. If it wouldn't, it would emanate EM waves, which would lead into energy dissipation

I have just explained to you above that a jump by means of a quantum fluctuation CANNOT generate energy that can dissipate, since the energy for the jump is generated by the QF, used to jump, and then returned: Thus according to the second law of thermodynamics NO ENERGY CAN BE DISSIPATED IN ANY MANNER!

Are you really so stupid or trying to jerk me off?
johanfprins
1 / 5 (3) Feb 23, 2013
@Natello, ValeriaT AKAK,

Hallooooo! Are you ONCE AGAIN claiming your right to remain silent in order not to incriminate your silly rubber-duck, swimming in its "high density" aether to cause waves relative to a non-existent inertial reference frame?

Tsk! Tsk! Tsk!
ValeriaT
1 / 5 (2) Feb 23, 2013
Good luck with your theory...;-)
johanfprins
1 / 5 (3) Feb 24, 2013
Good luck with your theory...;-)


Thank you. I accept that this means that you could not find flaws in my arguments. This, of course, does not mean that there might not be a flaw which will be discovered at a later time. But since nobody could to date point out a flaw based on experimental evidence and impeccable logic, I will not assume that it cannot happen in future: If it should happen, our understanding of physics will then be advanced: I promise, and hope that I will keep my promise, that if such a flaw is discovered I will not react like the mainstream crackpots who took charge of theoretical physics at the Solvay conference in 1927.

However, for as long as my theory and model cannot be flawed, it should NOT be censored from being published in the "peer-reviewed" journals as has been consistently done during the past 10 years. Such censorship, which has unfortunately become the rule in physics, constitutes treason against the future interests of humankind!
ValeriaT
1 / 5 (3) Feb 24, 2013
I accept that this means that you could not find flaws in my arguments.
Nope, I'm just realist. Your nonsensical denial of particle wave duality, entanglement and whole rest of contemporary quantum mechanics is way more apparent and fundamental, I spend dozens if not hundreds of posts in discussion with you about it - and yet you're not convinced about it less, than before whole discussion.

The discussion about superconductivity mechanism is way less subtle and it's based on correct understanding of quantum mechanics. You didn't demonstrate any progress in this regard, so for me it would be just a waste of time to continue with you in discussion at this specialized higher level.

I indeed do agree, your opinions about it shouldn't be censored in peer-reviewed press - no matter whether it's flawed or not. Actually such a publishing should be the very first step in subsequent discussion, whether it's flawed or not. The judgment of scientific community may only come later.
johanfprins
1 / 5 (3) Feb 24, 2013
I accept that this means that you could not find flaws in my arguments.
Nope, I'm just realist. Your nonsensical denial of particle wave duality, entanglement and whole rest of contemporary quantum mechanics is way more apparent and fundamental, I spend dozens if not hundreds of posts in discussion with you about it - and yet you're not convinced about it less, than before whole discussion.


You would have convinced me if you could have argued logically and answered questions in an and honest manner: But you are totally unwilling to give straight answers to simple questions: for example:

1. Define what a particle is and why is this concept at all required when doing quantum mechanics.

2. Explain when is an object, passing you by, "acting as" a "particle" and when it is "acting as" a wave.

3. Explain why the concept of "particle" is required when the Lorentz transformation PROVES that any object moving with speed v IS a coherent wave with wavelength equal to h/p?

ValeriaT
1 / 5 (2) Feb 24, 2013
Look, we aren't discussing some private concepts of mine here. The particle and wave concepts are used with all physicists over the world. So you should already know, what the particle is - or you're simply unqualified for any discussion about particle-wave duality. And because it's just you, who is doubting this concept (and not me) - my question is, if you don't agree with it, what your definition of "particle" and "wave" is?
johanfprins
2 / 5 (4) Feb 24, 2013
I accept that this means that you could not find flaws in my arguments.
Nope, I'm just realist. Your nonsensical denial of particle wave duality, entanglement

Where did I deny entanglement? Why do you ALWAYS hide behind GROSS lies?
and whole rest of contemporary quantum mechanics is way more apparent and fundamental

Contemporary QM claims that an electron (and a photon) can act like a "particle" OR "act like a wave" BUT NOT BOTH AT THE SAME TIME: Is your duck in aether, causing waves in the aether, in line with this contemporry QM? Or are you just blatantly lying again!
I spend dozens if not hundreds of posts in discussion with you about it - and yet you're not convinced about it less, than before whole discussion.

To convince me you should have argued logically and answered questions in an honest manner: But you have been deceitful and bent on propagating insane ideas which are NOT based on any experimental evidence, logic or "contemporary QM."
ValeriaT
1 / 5 (2) Feb 24, 2013
Contemporary QM claims that an electron (and a photon) can act like a "particle" OR "act like a wave" BUT NOT BOTH AT THE SAME TIME
Nope, it doesn't. At least from the time of Shahriar Afshar the mainstream physicists already know, that the wave-particle character CAN manifest itself at the SAME MOMENT and they already know too, it doesn't violate complementarity. If you don't know about it, then you're fighting with ghosts and barking on wrong tree.
BTW Every double slit experiment demonstrates it clearly for me: its results are never pure diffraction "flabelliform" pattern or pure particle points - but always the mixture of boths: the particle points arranged into diffraction pattern. Every child can recognize it.
johanfprins
1 / 5 (3) Feb 24, 2013
Look, we aren't discussing some private concepts of mine here.
Another blatant lie! It is all about your PRIVATE "duck in aether concept creating waves in such an aether which, since 1905, everybody knows cannot and does not exist!
The particle and wave concepts are used with all physicists over the world.

NOT in the way YOU use it!
So you should already know, what the particle is -
No I do not since not a single physicist in the history of physics could define what he/she means by the word "particle".
or you're simply unqualified for any discussion about particle-wave duality.
Unqualified because I ask for a definition of terms used in a discussion? I would think it is just the other way around: If a person cannot define the term "particle" he/she is using in an discussion, THAT person is unqualified to discuss "wave-particle duality". What are the characteristics of a "particle" that distinguishes it from a wave? Not once did you even try to answer this!
ValeriaT
1 / 5 (3) Feb 24, 2013
It is all about your PRIVATE "duck in aether concept creating waves in such an aether which, since 1905, everybody knows cannot and does not exist
LOL, we aren't discussing my dense aether model at all :-) We are talking about particle-wave duality, which is established concept of quantum mechanics from its very beginning - no less no more. Just keep the subject or I will stop to discuss about it at all.

BTW You still didn't present your definition of particle and wave concepts, so I still don't know, whether you're qualified for discussion about it or not. You've last chance for doing it right now, so please judge carefully your response this time.
johanfprins
1 / 5 (3) Feb 24, 2013
my question is, if you don't agree with it, what your definition of "particle" and "wave" is?

I do not define something that does not exists: Only a mentally disturbed person does that. I do not need to define the word "particle".
Such an entity does not exist since the Lorentz-transformation proves unequivocally that an electron, which is moving with a speed v and thus a momentum p=m*v, is a coherent wave of length (gamma)*D, where D is the diameter of the electron, and a coherent wavelength (lambda)=h/p. The electron itself is the wave: There is no "particle" moving past.
And as I have pointed out the Lorentz transformation is mandated by Maxwell's equations, so that the behavior of an electron as a coherent wave is also mandated by Maxwell's equations. There is thus no need to invoke the concept of "particle" which nobody from Newton to the present nincompoops in charge of mainstream physics has ever defined.
johanfprins
1 / 5 (3) Feb 24, 2013
Contemporary QM claims that an electron (and a photon) can act like a "particle" OR "act like a wave" BUT NOT BOTH AT THE SAME TIME
Nope, it doesn't. At least from the time of Shahriar Afshar..

Lying again! It is not accepted by the mainstream physicists that Afshar's experiment has proved that wave and particle behavior occurs simultaneously. Afshar's experiment was published by 'tHooft together with a plethora of manuscripts in which Afshar's interpretation was seriously challenged.
If you don't know about it, then you're fighting with ghosts and barking on wrong tree.
It is YOU who do not know the full story and thus making FALSE claims to keep your duck paddling. Have you got no shame whatsoever? Lies and distortions do not make physics!
ValeriaT
1 / 5 (2) Feb 24, 2013
I do not define something that does not exists
Sorry, your alleged nonexistence of particle-wave duality, it's complementarity the less doesn't imply the non-existence of particles and waves in their isolated form. The existence of complementarity considers the existence of particle-wave duality, the existence of this duality considers the existence of particles and waves. But no vice-versa. CONSIDERS ≠ IMPLIES.

You did lose the discussion with me this time. Have a nice rest of weekend.
johanfprins
1 / 5 (3) Feb 24, 2013
BTW Every double slit experiment demonstrates it clearly for me: its results are never pure diffraction "flabelliform" pattern or pure particle points -but always the mixture of boths.

A further exposition of your stupidity: All diffraction patterns are a superposition of single slit diffraction and double slit diffraction. This is actually proof that when a photon only moves through a single slit it contributes to the single slit pattern, and therefore, in order to contribute to the double slit pattern it MUST move through both slits simultaneously. Only a wave can do both: Move either through a single slit or through both slits simultaneously! Where is your particle?
the particle points arranged into diffraction pattern. Every child can recognize it.
But it takes an adult brain that is not mentally disturbed to interpret the result correctly!
ValeriaT
1 / 5 (3) Feb 24, 2013
BTW If you're really interested about dense aether predictions in this matter, try to imagine, what will happen during the double slit experiment with radiowaves. Short wavelength gamma ray photons manifest itself with tiny sharp spots arranged into flabelliform pattern. With decreasing energy density (i.e. increasing wavelength of photons) the spots at the target will become increasingly fuzzy - and when the wavelength will reach the wavelength of CMBR (~ 1,7 cm or so), the flabelliform patterns will become indistinguishable from pure diffraction patterns of pure waves. OK - it's trivial, despite the actually nobody did even realize it. Believe it or not, we still have no mathematical description of this dependence.

Anyway, the real question by now is - what will happen, if we increase this wavelength even more? And this is just the domain of AWT predictions regarding particle-wave duality. I can discuss only the AWT predictions with you from this moment, not your theory.
ValeriaT
1 / 5 (3) Feb 24, 2013
BTW In your theory ("everything is just a wave", "particle-wave duality doesn't exist") the result of double slit experiment should be always pure flabelliform pattern with no spots. In this way your schematic theory can be falsified immediately.

If the particle-wave complementarity would work, then we would observe the mixture of isolated spots distributed along Gaussian curve superposed with smooth flabelliform patterns - without any spots this time. Again, we already know, such a result of double slit experiment is impossible.

Such a conceptual thoughts are very trivial - but because both mainstream physicists, both you are using only formal schematic models for reasoning of their theories, you can never imagine these simple consequences and connections of formal "epicycle" models, based on numeric regression of reality, not its understanding. I can even admit, your theory may work quantitatively in certain extent - but the epicycle models gave quantitative predictions as well.
johanfprins
2 / 5 (4) Feb 24, 2013
we aren't discussing my dense aether model at all :-) We are talking about particle-wave duality,

Half-truths are also lies! You are clinging to the Voodoo concept of "wave-particle duality" since you believe that it "proves" your silly duck-aether model.
which is established concept of quantum mechanics from its very beginning - no less no more.

It has NOT been established by any experiment which cannot be interpreted purely in terms of wave behavior only.
Just keep the subject or I will stop to discuss about it at all.

Do it correctly and stop posting ideas which are purely based on Voodoo without any experimental support.
BTW You still didn't present your definition of particle
I told you clearly that only a demented mind will define something that does not exist!
wave concepts
Both the photon and the electron are electromagnetic waves which are well defined by Maxwell's equations. I can recommend elementary books that will explain EM-waves.
johanfprins
2 / 5 (4) Feb 24, 2013
I do not define something that does not exists
Sorry, your alleged nonexistence of particle-wave duality, it's complementarity the less doesn't imply the non-existence of particles and waves in their isolated form.
There are no isolated "particles" in any form. What you want to call "particles" are localized EM-waves: NOTHING ELSE.
The existence of complementarity considers the existence of particle-wave duality,
I know: That is why the concept of complementarity came from Bohr in a deranged moment!

is the existence of this duality considers the existence of particles and waves. But no vice-versa. CONSIDERS ≠ IMPLIES.
I wish I could make out what you are trying to say here! It is basically senseless as most of your posts are!

You did lose the discussion with me this time.
Where did I lose the discussion with you! You have not raised a single logical argument or quoted a single experiment to back up your so-called "arguments"!
johanfprins
2 / 5 (4) Feb 24, 2013
Anyway, the real question by now is - what will happen, if we increase this wavelength even more? And this is just the domain of AWT predictions regarding particle-wave duality. I can discuss only the AWT predictions with you from this moment, not your theory.

I am only quoting the last part of this nonsense posting by you. In the case of radio-waves, the detection of radiation is not limited to that of a "photon" energy h*(nu). You cannot construct a screen of atomically sized detectors that detect a radio-wave at these atomically sized detectors. Thus, you are again talking though your neck. Please do a course on Maxwell's equations and the generation and detection of radio-waves before posting such gobblygedook as you are posting now!
johanfprins
2 / 5 (4) Feb 24, 2013
BTW In your theory the result of double slit experiment should be always pure flabelliform pattern with no spots.In this way your schematic theory can be falsified immediately.
Only in your demented mind!
I have explained the diffraction of single photons many time in detail on this forum. The photon-wave moves through BOTH SLITS since it is a wave. The two entangled lobes that appear on the other side of the slits interfere to form a diffracted wave-front. When the diffracted wave-front reaches the screen, a detector in the screen cannot detect less energy than that of the photon: The photon has to collapse to the size of the detector and is thus observed as a spot! Consecutive photons resonate with different detectors so that spots are formed all over the screen. The provability of resonating with an atomically-sized detector is higher where the intensity of the diffracted wave-front is higher. Thus after many photons, the spots add to form the diffraction pattern.
johanfprins
2 / 5 (4) Feb 24, 2013
Such a conceptual thoughts are very trivial - but because both mainstream physicists, both you are using only formal schematic models for reasoning of their theories, you can never imagine these simple consequences and connections of formal "epicycle" models,
Your model is an "epicycle" model based on nonsense with no experimental support.
ValeriaT
1 / 5 (1) Feb 24, 2013
The photon has to collapse to the size of the detector
So do you agree with collapse of quantum wave of Copenhagen model/interpretation of QM? So far my feeling was, you're denying it too...
johanfprins
2 / 5 (4) Feb 24, 2013
The photon has to collapse to the size of the detector
So do you agree with collapse of quantum wave of Copenhagen model/interpretation of QM? So far my feeling was, you're denying it too...
I have posted OVER and OVER and OVER and OVER and OVER, that a wave changes shape and size when its boundary conditions change. Thus, to be detected by an atomically-sized detector, the wave has to collapse to the size of the detector. When it encounters a double slit, the wave has to inflate and move through BOTH slits. Thus obviously when the extended diffracted wave-front of a photon reaches the screen, the wave must collapse to the detected.

However, the Copenhagen interpretation states that it is NOT a actual wave that collapses, but a probability-distribution, and that this probability-distribution collapses to give "birth" to the position of a "particle". I reject this interpretation of "wave-particle" collapse since it leads to Voodoo concepts like multiverses etc.!
Tausch
2 / 5 (4) Feb 24, 2013
Q.
If superconductivity is a property, then is there a consensus to what that property is?

Your choices are:
1.Ans)intensive
2.Ans)extensive
3.Ans)neither
ValeriaT
1 / 5 (2) Feb 24, 2013
The onset of superconductivity is measurable quantitatively. The current/magnetic field limit can be measured quantitatively as well. The choice of superconductor for LHC for example is therefore quantitative, not just qualitative one. Without it it wouldn't matter which superconductor we will use.
johanfprins
2 / 5 (4) Feb 24, 2013
If superconductivity is a property, then is there a consensus to what that property is?

There will not be as long as there is no real physics-model on which everybody agrees. Superconduction within a material has a critical temperature below which SC is possible. All models agree that below this temperature the charge carriers has a high enough density to allow SC. In the accepted mainstream models like the BCS model, it is claimed that at this critical temperature the charge-carriers form a Bose-Einstein Condensate which allows cooperative "in phase" motion of all the charge-carriers. Since according to the accepted models, such a condensate can supposedly only form when the charge-carriers are bosons, they invented Cooper pairs where two electrons are "glued" together by virtual phonon-exchange.
To form a Bose-Einstein Condensate the bosons must entangle, and I have discovered experimentally that this demands that they must lose their existences as separate entities.
johanfprins
2 / 5 (4) Feb 24, 2013
If there are not separate Cooper pairs, these entities can clearly not act as charge-carriers that convey a current through a material. Thus if you have separate charge-carriers, as you have within a material, these charge-carriers cannot constitute a Bose-Einstein condensate.
Nonetheless it is correct to state that all the SC charge-carriers must each have the lowest energy that each one of them can have, or else they will have energy which they can scatter away.

Thus you need charge-carriers which are distinguishable as separate entities; where each charge-carrier has the same lowest energy than the other charge-carriers. If the charge-carriers must remain separate entities, they are distinguishable: This means that neither Bose-Einstein, or Fermi-Dirac statistics apply. Simple Boltzmann statistics, which is valid notwithstanding the spin of the charge-carriers is thus sufficient.

I have to attend to other matters: Back later!
johanfprins
2 / 5 (4) Feb 25, 2013
Simple Boltzmann statistics, which is valid notwithstanding the spin of the charge-carriers is thus sufficient.


Boltzmann statistics prevail when there are two possible energy-states (having an energy gap E between them) for an ensemble of identical separate entities where the population densities of the two energy states are determined by an activation-energy. That the temperature characteristics of superconduction is in all cases determined by Boltzmann statistics can be seen from ALL experimental data on SC, as a function of temperature, which have been measured to date.

But, as we should all agree, the SC charge-carriers must form from the valence electrons that bond a solid together; and it is common cause that the energy distribution of these bonded electrons is determined by Fermi-Dirac statistics. So how can Boltzmann
statistics come into play?

This happens when there is a SUITABLE energy-gap within the energy-spectrum of these valence electrons: (continue)
johanfprins
2 / 5 (4) Feb 25, 2013
This happens when there is a SUITABLE energy-gap within the energy-spectrum of these valence electrons:


1. Consider for example a perfect crystal of germanium: It has a valence band (VB) and a conduction band (CB) separated by an energy E. At normal temperatures, there are pseudo-electrons in the CB and holes in the VB: The density of charge-carriers within the CB (and this also within the VB) is determined by the activation energy Ea of the Boltzmann-factor exp(-Ea/kT). The Fermi-Dirac factor thus extrapolates to become this Boltzmann-factor. In turn, the activation energy of this Boltzmann-factor is determined by the position of the Fermi-level within the energy-gap E. In the case of germanium Ea is approximately E/2; which is easily verified experimentally.

2.Another example is donor electrons when doping say silicon with phosphorus. At T=0, the donor electrons ALL have the SAME energy which is Ed below the conduction band, and the Fermi-level is also at this energy.

johanfprins
2 / 5 (4) Feb 25, 2013
At T=0, the donor electrons ALL have the SAME energy which is Ed below the conduction band, and the Fermi-level is also at this energy.

Thus, at T=0, the activation energy of the Boltzmann factor is Ea=Ed. But when the temperature now increases, the Fermi-level rises to higher values, so that the activation-energy decreases from Ed until it becomes zero when it enters the conduction band.

Once within the conduction band "normal conduction" dominates, where charge-transport is by wave-packets within the CB. At lower temperatures, when the Fermi-level is below the conduction band, "normal conduction" within the CB is competing with hopping of the localized stationary donor-electrons at the energy Ed, below the CB. There must thus be a critical temperature below which this hopping conduction dominates, and above which "normal conduction" within the CB dominates. This will appear as a "phase-change".

The mainstream nincompoops call the latter critical temperature a "pseudogap".
johanfprins
2 / 5 (4) Feb 25, 2013
The mainstream nincompoops call the latter critical temperature a "pseudogap".


If the energy-gap Ed is small enough, and the density of localized electron-states becomes high enough below a critical temperature, "normal-hopping" becomes SC-hopping: This is allowed by the Heisenberg relationship for energy and time (NOTE I AM NOT USING THE WORD "UNCERTAINTY RELATIONSHIP"), the localized pseudo-electron can borrow enough energy (delta)E to break-free and enter the CB, and in addition have the kinetic-energy to move to an adjacent position within the ALLOWED time interval (delta)t, and then "return" the energy from where it came. Thus (delta)E=Ed plus (1/2)*m*v^2; and (delta)E*(delta)t=g*(hbar); where g is a constant that is determined by the shape and size of the localized pseudo-electron wave.

Since the energy to move is supplied by a quantum fluctuation, acceleration is not required, and there is no permanent increase in kinetic energy which needs to be dissipated.
johanfprins
2 / 5 (4) Feb 25, 2013
Since the energy to move is supplied by a quantum fluctuation, acceleration is not required, and there is no permanent increase in kinetic energy which needs to be dissipated.
Transport with no energy dissipation: ergo SC.

Thus, you need an energy-gap Es between stationary, localized pseudo-electrons, and higher-energy delocalized electronic states (which can superpose to form wave-packets to, in this way, conduct "normally"). The larger Es is, the higher the density of the localized states must be for SC to be possible. If the maximum density of localized states is too low for the energy gap Es, no SC is possible. In order to increase the critical temperature for SC one has to increase Es, provided one can increase the density of the localized pseudo-electrons to a high enough density.

This is the difference between the ceramics and the low temperature metals: The possible densities of donor-states are far higher within the ceramics than within the metals.

johanfprins
2 / 5 (4) Feb 25, 2013
The possible densities of donor-states are far higher within the ceramics than within the metals.


The ceramics also have the advantage that they can, in some cases, be extrinsically doped to increase the donor-density so that the density of localized pseudo-electrons can be increased, which in turn allows higher critical temperatures.

Ideal metals like copper, gold etc. have no localized pseudo-electron states, and cannot be extrinsically doped to have localized states. Thus they cannot be superconductors, except when you "amorphize" them to form localized states by means of the Anderson mechanism. The latter has been done experimentally.

In the case of non-ideal metals, intrinsic localized states are possible. Eugene Wigner was the first to derive this possibility theoretically already in the 1930's. He concluded that these states should be electronic states formed in each case by the harmonic vibration of a pseudo-electron through an induced positive charge.
johanfprins
2 / 5 (4) Feb 25, 2013
He concluded that these states should be electronic states formed in each case by the harmonic vibration of a pseudo-electron through an induced positive charge.


It is easy to show that such a state will be critically affected by the isotopic mass of the surrounding atoms! Thus if Wigner's derivation is correct (and I think it is!) SC through such metals must be a function of the isotopic mass of the atoms: The isotopic dependence of SC in the low temperature metals might thus not be caused by virtual phonon exchange to form Cooper pairs.

Further support for the latter conclusion is the measurement of the activation-energy for a low temperature SC. It starts off at zero when the Fermi-level moves into the gap Es (which does not itself change with temperature) and then increases as the Fermi-level moves down to be at the energy Es at absolute zero temperature. Thus, this activation energy has nothing to do with the bonding-energy of a Cooper pair.

Any intelligent questions?
johanfprins
2 / 5 (4) Feb 25, 2013
Why they shouldn't and another metals do have such a localized states? This is just a question, which theory should be able to answer.

I thank you for a relevant question.
Both theory and experiment answers this very well:

An ideal metal is defined as a metal within which the valence electrons bonding the metal-ions, are so well screened from the positive charges on these ions and from one another that you can model the energy states by assuming that you only need to solve Schroedinger's equation for a single "free"-electron subject to the boundary conditions of the metal: i.e. its surfaces on which one can assume to first order that the intensities of the allowed electron-waves become zero. The spectrum of allowed energy-states are then delocalized, stationary waves, each of which fills the whole metal.

Metals like copper, gold etc. give measured electronic states which are in close agreement with this. It is relatively safe to conclude that the waves are not localized.
johanfprins
2 / 5 (4) Feb 25, 2013
It is relatively safe to conclude that the waves are not localized.

When the screening is not so good, one obtains non-ideal metals within which the electrons do experience the positive charges on the ions more intensely. You then get energy gaps to appear within the electronic energy spectrum. When these gaps are small, you can still have metallic conduction. If the screening becomes even worse, the gaps become so large that the material becomes an insulator, and depending on the stochiometry of the insulator these materials can also have intra-band, localized electronic wave states.

Wigner derived that such states can also form within the small band-gaps of your non-ideal metals, and that these states are caused by localized vibrations of pseudo-electrons through localized induced positive charges. Within the ideal metals the screening of the valence-electron waves are not low enough to allow such localized states to form. Ergo: Ideal metals do not form SC phases.
johanfprins
2 / 5 (4) Feb 25, 2013
Within the ideal metals the screening of the valence-electron waves are not low enough to allow such localized states to form. Ergo: Ideal metals do not form SC phases.


To emphasize: "Within the ideal metals the screening of the valence-electron waves are enough NOT to allow such localized states to form"

Minich
1 / 5 (3) Feb 26, 2013
Twaddle,
named by johanfprins, THE THEORY.
...kindergarten....
johanfprins
1 / 5 (3) Feb 27, 2013
Twaddle,


Correct! I am glad that you realize that twaddle is all you know and can post! I bow to the master!