Watching the Tug of War between Structure and Superconductivity

Apr 15, 2010
The crystalline structure of the superconductor FeSe has square layers of iron (Fe) atoms that are strongly chemically bonded to layers of selenium (Se) atoms. The superconducting electrons are found in the iron layers. The group's work showed that a deviation of the shape of the iron layers from exactly square geometry at the length scale of thousands of atoms is a critical factor in determining whether superconductivity occurs or doesn't occur.

(PhysOrg.com) -- Like Clark Kent, who often forgoes his social life to become Superman, materials that become superconducting must sacrifice at least one of their natural properties to attain the ability to transfer electric current with zero resistance. At the NSLS and Brookhaven's Center for Functional Nanomaterials (CFN), a team of researchers has explored this internal conflict in a class of iron-based superconductors, materials that could be used to develop energy-saving applications such as high-efficient power lines.

Relatively new to the field of superconductivity, iron-based materials are now world-famous for their frictionless transport of electrons at "high" temperatures — above about 50 Kelvin, or -190 degrees Celsius.

"Iron-based superconductors have second highest that anyone knows about, a characteristic that's very important if we want to use them for practical applications," said Princeton researcher Robert Cava. "All aspects of research on these materials are now underway. Our part of the picture is to try and understand why they're superconducting in the first place."

Cava and a group of fellow researchers from Princeton, Stony Brook University, Brookhaven, and Johannes Gutenberg University, in Germany, focused their investigations on a particular material made from conducting layers of iron and selenium, called iron . In recent years, scientists have explored numerous aspects of the underlying physics of iron-based superconductors, often making connections to the material's structure or innate magnetism. But the exact relationships between these properties were unclear.

"In order for superconductivity to exist, it must arise as the winner in a tug of war between different physical properties," Cava said. "The research community has known that magnetism competes with superconductivity in the iron , but no one had a good idea of how crystal structure competed."

Cava's group compared the structures of superconducting and non-superconducting iron selenide using two different types of tools: powerful beams of x-rays at the NSLS and a suite of advanced microscopes at the CFN. At NSLS beamline X16C, the researchers used synchrotron x-ray powder diffraction to provide "snapshots" of the materials on the order of hundreds of nanometers. They combined that data with images taken with transmission electron microscopy and electron diffraction, resulting in resolution an order of magnitude higher than the x-ray technique.

"We needed both of these sophisticated techniques to really understand what was going on here," Cava said, adding that the findings weren't as straightforward as expected.

Among the results, which were published in the July 31, 2009 edition of Physical Review Letters, the group showed that the superconducting form of iron selenide can be distinguished from the non-superconducting form by a change in its structure. The superconductor gains its power by giving way to a slight structural "distortion," and the non-superconductor holds strong.

The researchers also showed that this unique structural change is unrelated to magnetism, as hypothesized in the past. The material's fundamental bonding — the bonding between atoms — stays the same while the angles between the bonds change, similar to the expansion of a baby gate. Unlike a gate, the angles only change by a few degrees — still enough, though, to give birth to superconductivity.

But the real surprise is that this structural change actually exists in both the superconducting and non-superconducting forms of the material, just on different scales and with different effects.

"This distortion can still be found in the non-superconducting material, but it's only present over tens of atoms," Cava said. "In the superconducting material, it's present over very long distances. This detail was hidden until we were able to take a really close look at the materials. The challenge now is to figure out over what distance a has to be distorted in order to affect its properties."

Next, Cava's group will try to resolve the structure-superconductivity relationships within other iron-based .

"By showing the scientific community this clear example, we hope to inspire them to think about manipulating this phase transition," he said.

Explore further: Scientists uncover clues to role of magnetism in iron-based superconductors

More information: T.M. McQueen, A.J. Williams, P.W. Stephens, J. Tao, Y. Zhu, V. Ksenofontov, F. Casper, C. Felser, R.J. Cava, "Tetragonal-to-Orthorhombic Structural Phase Transition at 90 K in the Superconductor Fe1.01Se," PRL, 103, 057002 (2009).

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jimbo92107
4 / 5 (2) Apr 16, 2010
I wonder if a properly tuned acoustic wave form might induce a superconducting phase change in certain materials.
Parsec
4 / 5 (1) Apr 16, 2010
I was thinking the same thing. I was wondering if physically straining the crystal lattice could increase the critical temperature. It also seems to me that by chemically modifying the base compounds so that the structure is naturally strained, if this is a route to higher temp superconductors.
axemaster
1 / 5 (1) Apr 16, 2010
An interesting point; however acoustic waves would probably take the form of EM waves... I'm not sure how EM waves behave inside a superconductor, but at a certain freq they might have some effect. Of course if they trigger superconductivity, the state change would affect the influence of the EM waves, and might result in an oscillation, which could heat the material...

It's a tough problem.
broglia
1 / 5 (3) Apr 16, 2010
As I explained already here, superconductivity arises, when movable electrons are lured on rows of positivelly charged atoms (hole stripes) like bees to honey. The chaotic motion of compressed repulsing electrons around stripes is what forms stripes of superconductive phase. I don't think, introduction of sound waves could improve such situation.

BTW It's not true, the iron pnictides are the 2nd highest Tc superconductors. The web superconductors.org presents superconductors, the Tc of which surpases 250 K.

http://www.superc...254K.htm

These materials are formed by layered structures of hole stripes, which are separated as much as possible. The dilution of hole stripes enables to excert higher pressure of neighbouring atoms to electrons, participating to superconductivity from outside. Of course, the same dilution decreases the probability, that the hole stripes in individual layers would form a continuous phase. Such materials would perform well only in perfect crystal.
broglia
1 / 5 (3) Apr 16, 2010
Currently the only trick in preparation of these materials is to introduce a substitute atoms into crystal lattice, which differ only slightly from size and another properties. Such atoms tend to form highly aperiodic structures, simmilar to hyperlattices, used in heterojuctions by semiconductor industry.

Unfortunatelly, the same mechanism leads to formation of amorphous structure, simmilar to properties metallic glass. Amorphous metals are usually formed by mixtures of atoms, which are of quite simmilar properties, which makes their crystallization more difficult.

http://www.physor...592.html

As we can see, the formation of high Tc superconductors by using of mixed atoms is controversial - the more sparse lattice we get, the more hardly it crystallizes into fully regular structure. In this way, the higher Tc we get, the less pronounced is the superconductive transition.
johanfprins
1 / 5 (1) Apr 16, 2010
ALL superconducting phases ALWAYS consist of an array of localised, anchored electronic-states. When the binding energy of susch a state is low enough, and the distance to the next state is small enough, a quantum fluctuation allows such a state to gain the required energy to break lose and move to the position of the next localised state; which in turm repeats the process. Thus the kinetic-energy required for the movement does not remain to be dissipated.
Thus any change in a superconductor which increases the binding energy of such a localised state while at the same time decreasing the distance between states so that a quantum fluctuation can occur, increases the critical temperature. That is why pressure can do this since it decreases the distances between the localised states. It is a simple case to prove that the ceramic superconductors can at best reach a Tc of 250 K; since the distances betwee suitable localised states cannot become smaller. See extract 23: cathodixx.
broglia
1 / 5 (2) Apr 16, 2010
The superconductor hyperlattice could be artificially in simmilar way, like so called damascus steel. The question is, if we can really achieve the regular structure of ceramic materials at atomar level in such way, because ceramic materials are brittle. This research is quite different from development of superconductivity theories and even good theory of high Tc superconductivity doesn't ensure, we will be able to prepare corresponding material.
broglia
1 / 5 (2) Apr 16, 2010
ALL superconducting phases ALWAYS consist of an array of localised, anchored electronic-states..
Why not, but the number of electrons in arrays of Type I superconductors is only two due the bilateral nature of spin-spin interactions. In this way the BEC mechanism switches into BCS mechanism at low temperatures. The rest of your comments has no meaning for me, but their clarification would probably exceed the scope of this forum.
in7x
5 / 5 (1) Apr 16, 2010
I agree with Jimbo and Parsec.

Cool the sample, deduce it's superconducting "harmonic frequency", maintain that frequency, then raise the temperature and observe.
yoron
not rated yet Apr 16, 2010
Wonder if we're going to be able to use lasers for constructing a super-conductive transport chain for electrons. Transport 'electricity' by light tweaked to resemble a structure, perhaps inside fibers, and at room temperature? Too SF?
johanfprins
1 / 5 (1) Apr 16, 2010
. but the number of electrons in arrays of Type I superconductors is only two due the bilateral nature of spin-spin interactions. In this way the BEC mechanism switches into BCS mechanism at low temperatures.

Both BEC and BCS play NO role in superconducting phases within materials whatsoever. As I have already explained before: When modelling the EM-radiation from a Josephson junction in terms of quantum mechanics (and not in terms of a classical ac-current, which is wrong physics) one finds irrefutable evidence that the charge-carriers are SINGLY charged.
The only superconducting phase which is a BEC is the one generated by electron-entanglement between an n-type diamond and an anode. In this case there is no separate charge-carriers since the electrons totally lose their separate identies during entanglement. A BEC is a single wave not a collection of separate entities. THus superfluid helium, although a minimum energy state, is NOT a BEC.
johanfprins
1 / 5 (1) Apr 16, 2010
Wonder if we're going to be able to use lasers for constructing a super-conductive transport chain for electrons. Transport 'electricity' by light tweaked to resemble a structure, perhaps inside fibers, and at room temperature? Too SF?

Wnderful idea: If you could create a lattice of electrons with light beams so that the distances between the electrons become small enough, the system must be a superconductor. You should have patented this idea unstead of posting it in the public domain!
Skeptic_Heretic
not rated yet Apr 16, 2010
THus superfluid helium, although a minimum energy state, is NOT a BEC.

Thank you, everyone tends to screw this part up and it's been hurting SC research due to ignorant preconception.
Slotin
1 / 5 (2) Apr 16, 2010
[. A BEC is a single wave not a collection of separate entities.

This is just an ad-hoced definition of yours. Is this stuff a BEC or not?

http://physicswor...w1405031
johanfprins
1 / 5 (1) Apr 16, 2010
This is just an ad-hoced definition of yours. Is this stuff a BEC or not?

No ad-hoc: It follows directly from the analogy of black body radiation which consists of standing waves; each being a single wave which is an entanglement of waves each having a quantum of energy. Quanta do not exist individually within a black-body cavity since their allowed energies are determined by the boundary conditions of the standing waves. Thus if Einstein's derivation is correct that "particles" with mass form a lowest energy BEC, this BEC must also be a single standing wave: Not a collection of separate particles.
I could not access the website you you proposed I should visit. It seems that Im have to register again with Physorg.com. Why I have to, I do not understand.
seneca
1 / 5 (3) Apr 16, 2010
This picture should be accessible 4you without registration - does it illustrate BEC - or not?

http://images.iop...5031.gif
Auxon
not rated yet Apr 17, 2010
Wonder if we're going to be able to use lasers for constructing a super-conductive transport chain for electrons. Transport 'electricity' by light tweaked to resemble a structure, perhaps inside fibers, and at room temperature? Too SF?

Wnderful idea: If you could create a lattice of electrons with light beams so that the distances between the electrons become small enough, the system must be a superconductor. You should have patented this idea unstead of posting it in the public domain!


He has one year from the time of posting to the public domain to patent.

SASERS ... http://en.wikiped...adiation
johanfprins
3 / 5 (2) Apr 17, 2010
This picture should be accessible 4you without registration - does it illustrate BEC - or not?

In principle not: Since it consists of seperate observable entities: However, in quantum mechanics the apparatus used to "observe" an entity can modify the characteristics of the entity. There exists the possibility that the seperate spots could merge to form a real BEC when no measurement is made.
Consider the following related situation: We claim that a metal contains "free electrons". This is not possible since every electronic-state has an energy which is less than the rest mass of an electron. Fuirthermore we have no direct experimental proof that there are free charge-carriers when we do not apply an electric-field to the metal. In fact the evidence is compelling that at low temperatures there are no free charge carriers when there is no electric-field being applied; and that the application of the electric field generates wave packets which then act as charge carriers.
Skeptic_Heretic
5 / 5 (1) Apr 17, 2010
[. A BEC is a single wave not a collection of separate entities.

This is just an ad-hoced definition of yours. Is this stuff a BEC or not?

http://physicswor...w1405031

That isn't an ad hoc, that's the actual definition. Again proving your knowledge of science to be wanting, seneca.
seneca
1 / 5 (3) Apr 17, 2010
That isn't an ad hoc, that's the actual definition.
This is indeed easy to say, but I never saw any evidence of the claims of yours.

http://en.wikiped...ndensate

In this reference article BEC state is defined by its lowest quantum state and no condition about "single wave" behavior was ever mentioned there. By the definition of yours or J.F.Prins's we should rewrite a thousands of articles about BEC. Because we could never talk about vortices in BEC and many other stuffs, demonstrating non-single-wave behavior of particles in BEC. And whole this discussion is OT.
johanfprins
1 / 5 (1) Apr 17, 2010
...article BEC state is defined by its lowest quantum state and no condition about "single wave" behavior was ever mentioned there.

You make a good point: In the standard literature no distinction is made between separate entities all having the same energy, and a single macro-wave. This state of affairs has been caused by Bohr's complementarity which distorted all physics.
Einstein came to a BEC by reworking Bose's statistics for quanta. The fact is that are no separate quanta in cavity radiation. Each of the standing waves consists of an entanglement of quanta which are not separate entities once they form part of the standing wave. Thus if light could have had a ground-state wave, it would be a
single macro-standing wave without separate quanta. Thus by analogy a BEC must be such a wave: The BEC's generated from suitable atoms at very low temperatures are such waves; or else they would not be able to diffract. Diffraction fringes have been observed.
johanfprins
1 / 5 (1) Apr 17, 2010
By the definition of yours or J.F.Prins's we should rewrite a thousands of articles about BEC. Because we could never talk about vortices in BEC and many other stuffs, demonstrating non-single-wave behavior of particles in BEC.

It has to be rewritten: That you can see vortices etc. in superfluid helium and superconduction is proof that these phases are NOT BEC's, but just low energy phases within which all the separate constituents have the same energy. In superfluid helium each atom is a BEC, not all of them together. In a metal an array of localised states can form where each state has the same energy without having to be a boson (e.q. an array of localised donor-electrons). Movement can occur in both cases by means of quantum fluctuations. Within a material the array can be separate fermions: One does not require bosons and therefore electron-pairing: When analysing radiation from a Josephson junction correctly it is found that the charge-carriers have single charges.
seneca
1 / 5 (3) Apr 17, 2010
..one does not require bosons and therefore electron-pairing.. versus.. all superconducting phases consist of an array of electronic-states...
So we can say, BCS theory is based on two-member arrays of electronic states, thus fulfilling both official theory of superconductivity, both theory of yours. You're fighting with ghosts.
johanfprins
1 / 5 (1) Apr 17, 2010
So we can say, BCS theory is based on two-member arrays of electronic states, thus fulfilling both official theory of superconductivity, both theory of yours. You're fighting with ghosts.

That is of course possible. If these charge-carriers have a double charge, the flux quantum trapped by them will be half as much than is measured experimentally for the low temperature metals.
I think, correct me if I am wrong, that there have been cases when one half a flux quantum has been measured. In these cases the charge-carriers might be doubly-charged: However, the fact that this is possible does not demand that the charge-carriers MUST be doubly-charged. They do not have to be and in the low temperature metals that I know off, they are NOT.
seneca
1 / 5 (3) Apr 17, 2010
For me it's rather interesting, if this device could be working. It's formed by wire covered by thin insulating layer of diamond or boronnitride inside of vacuum. The free electrons are attracted to this layer by external electrical field by using of counter-electrode, surounding the bornitride layer.

http://tinyurl.com/y8xtr7n

At the certain intensity of electrical field the electrons should form a superconductive phase covering bornitride layer, which could be used as a superconductive wire. It's superconductivity could be switched by external electrical field on/off, so it could serve as a sort of transistor or even amplifier.
johanfprins
1 / 5 (1) Apr 17, 2010
@ seneca,
Very good! Except that the polarity you are using will counteract the formation of a superconducting layer. Similar structures with the correct polarity are covered by my patent which will be in the public domain in 18 months time.
seneca
1 / 5 (2) Apr 17, 2010
I'd rather patent just the opposite polarity, being you...;-)
johanfprins
1 / 5 (1) Apr 17, 2010
I'd rather patent just the opposite polarity, being you...;-)

Go ahead! And good luck!
seneca
1 / 5 (3) Apr 17, 2010
In your experiments you used a positively charged particles of oxygen plasma to inject positive ions beneath diamond surface. In the superconductor switch device the particle used are electrons, i.e. of the negative charge. They're not injected bellow diamond surface, just attracted to it by electrostatic force and compressed into superfluid in such way.

Anyway, positively charged particles like hydrogen ions and/or alpha particles could work as well or maybe even better (electrons would tunnel through insulator layers rather readily). The cloud of highly compressed deuterons could become significant with respect to cold fusion. And every layer of superconductive fluid of carged particles could behave like antigravity shielding because it should reflect just the gravitational waves.

In such way, such device could have many potential uses not just for superconductivity. Unfortunately, mainstream physics cares rather about black holes in LHC and other explosive stuffs.
johanfprins
1 / 5 (1) Apr 17, 2010
@ seneca
You are hearing the bell tolling but do not know where the tongue is. I am not going to argue with you in detail on your statements since I will have to violate the instructions of my patent lawyers. Suffice to say that your moments of brightness spring forth from very woolly logic.
seneca
1 / 5 (3) Apr 17, 2010
Every patent should be freely available - or not? It doesn't matter, what your lawyers said you about it. I'm just following the info in the publication of yours.

http://www.iop.or...8/3/319/
johanfprins
1 / 5 (1) Apr 18, 2010
Every patent should be freely available - or not? It doesn't matter, what your lawyers said you about it. I'm just following the info in the publication of yours.

Only adfter it has been vetted by the patent examiners. This is simple logic is it not?
I could not open the website that you have indicated but I assume it refers to my publications in Semiconductor Science and Technology. That is in the public domain; but I have since moved on much much further!
seneca
1 / 5 (2) Apr 18, 2010
..patent which will be in the public domain in 18 months time
Who will pay for such patent?
johanfprins
1 / 5 (1) Apr 18, 2010
Who will pay for such patent?

Companies which want to manufacture processor chips which are faster than any present ones and which generate no heat. As somebody from IBM has said "light speed sucks".
seneca
1 / 5 (3) Apr 18, 2010
It took ten years to use strained silicon after this technology was patented - and this is just a minor change of silicon technology. Why companies, producing processor chips should pay for patent of technology, which becomes public domain in 18 months without the least chance to use such technology during next two years?
johanfprins
3 / 5 (2) Apr 18, 2010
It took ten years to use strained silicon after this technology was patented - and this is just a minor change of silicon technology. Why companies, producing processor chips should pay for patent of technology, which becomes public domain in 18 months without the least chance to use such technology during next two years?

Maybe you are correct: But I will still have the determining patent if they do decide otherwise. In fact all superconduction above 250 K and higher is covered by my patent. So if they do not want to use it in the West, there are other alternatives.
Bonkers
not rated yet Apr 19, 2010
Oh Seneca, with such an understanding of anti-gravity shields, and the fundamentals of high temperature superconductivity, cold fusion and faster-than-light travel at your fingertips, you appear less well versed in the fundamentals of patents. These are put into the public domain not as a free gift to any potential users but as a deal between the inventor, who can charge for their use for a period of time, and society, which captures the knowledge and eventually owns it.
seneca
1 / 5 (3) Apr 19, 2010
In most countries the term for patents is 20 years, after which the invention becomes part of the public domain. I presume, it's the case of J.F.Prins's patent(s), too. So - does public domain mean free usage or not?

http://en.wikiped...c_domain

I wish prof. Prins his well deserved money for his finding, but my understanding is, the general lack of further publications could mean A) this finding doesn't work B) this finding is developed in secret.

It's well known, Stalin initiated research of Soviet nuclear bomb just because all publications about uranium fission disappeared suddenly from western journals in the late 1930s.
johanfprins
1 / 5 (1) Apr 20, 2010
@seneca,
Public domain means that the patent has been allowed by the patent examiners. The patentee then has sole rights for 20 years. All patentable material is developed "in secret" until allowed by the patent examiners. The extraction of electrons from an n-type diamond to form a SC phase is in the public domain and this stops npobody from reproducing it provided he/she is a competent physicst. During the past 10 years I have met very few physicists who are competent enough. Probably due to the fact that in 1927, they all became bipolar by believing in wave-particle duality.
broglia
1 / 5 (2) Apr 20, 2010
Public domain means that the patent has been allowed by the patent examiners

Do you mean granted like at the case of this guy? This is a different step, IMO.

http://www.chron....891.html

Anyway, everything appears clear for me by now.
johanfprins
3 / 5 (2) Apr 20, 2010
@broglia,
Yes the world would have been so much better for ALL of us if rge oldest profession in history, the so-called LEGAL PROFESSION, did not have such grip on us. The worst is that THEY claim that they stand for "JUSTICE": Something that NEVER existed antwhere under ANY government in the world.
Why do they blame prostitution: At least it provides some pleasure: something that the oldest profession does not. They screw you both ways.
Slotin
1 / 5 (2) Apr 20, 2010
Yep, this is why I'm not patenting my ideas. But it's completely my private philosophy - I can understand, why for many people the existence of patent laws is still motivation of their further research.

As the number of human knowledge & ideas will increase, we can expect gradual decline of patents in technical areas in similar way, like we can observe the decreasing of significance of patent law in software industry.

In this industry patents are already serving just for prohibiting the other people to earn money just by patenting the same thing in advance (Eolas activity with respect to MS ActiveX technology and many others).

Such patents are indeed losing their original meaning - they're becoming the brake of technical progress, instead of its protection. This is just another evidence of supersymmetry in human society: every principle becomes its own violation in less or more distant perspective and it should be upgraded.
johanfprins
1 / 5 (1) Apr 21, 2010
@Slotin,
It becomes clear that we need a massive rethinking about the knowledge-creating industry. At present there is no protection for the 'garage-inventor" like myself.
Skeptic_Heretic
not rated yet Apr 21, 2010
At present there is no protection for the 'garage-inventor" like myself.


Well, there is protection, you just can't afford it on a garage inventor's salary.
johanfprins
1 / 5 (1) Apr 23, 2010
Well, there is protection, you just can't afford it on a garage inventor's salary.

Protection should mean justice! According to every democratic constitition it is claimed that all citizens are equal before the law. This is obviously not true since the majority of citizens do not have the money to be "equal before the law".
Alizee
Apr 23, 2010
This comment has been removed by a moderator.
johanfprins
1 / 5 (1) Apr 24, 2010
This is the same stuff like health care or access to education, which is basically free in most countries, but you can always buy a much better one on private basis.

Yes it is: But then it should not be stated in the constitution of a country that everybody is equal: THe fact remains that in ALL countries I know off George Orwell's dictum in Animal Farm is valid: "Some animals are more equal than others!"

It should be stated that all these promises in the constitution are valid IF you can afford it: And even then you will most probably still be screwed.
Macksb
1 / 5 (1) Apr 24, 2010
The key point here is the precise angle created by the structure. There are two sets of oscillating waves emerging from different points in the lattice. They intersect at an angle, which is itself determined by the structure. At the intersection, the two sets of waves or oscillations form a seiche. (Sailors know the term.)

If the angle is perfect, the seiche, which is a set of perfectly synchronized oscillations, extends throughout vast areas of the material. If the angle is not perfect, the seiche, if it forms at all, is too small to be effective.

To determine the precise angle, study the pnictide experimental observations announced by Riken (Japan) on April 22. The pictures they show are of the seiche itself; and they describe the waves that intersect. Study the frequency of those two types of waves, simulate them on a computer, and then derive the exact angle between the two sets of waves.

Superconductivity in all forms emerges from synchronized oscillations.
johanfprins
1 / 5 (1) Apr 25, 2010
Superconductivity in all forms emerges from synchronized oscillations.

When you have a superconducting element between two contacts in a circuit, it must surely transport charge injected into it at any rate up to its maximum current. Thus if you slow down the injection rate to say only enough charge for one superconducting charge carrier per hour (or per day or per year), how does this small amount of charge cause synchronised oscillations over the whole body of the superconductor?
It should be noted that all the accepted models on superconsuction, like the BCS model, cannot explain this fact since it is assumed that all the charge carriers must move coherently. Why would they do this if only the charge on a single charge-carrier has to be transported from the injection contact to the ejection contact?
Macksb
1 / 5 (1) Apr 26, 2010
Johan:

Thanks for your question. I have made my point about synchronized oscillations as the key to understanding superconductivity on several physics blogs. If you Google Macksb physics you will find the posts.

When I refer to synchronized oscillations, I am referring to synchrony of certain oscillations within the material itself. If I read your question properly, you seem to be focused on the current that flows smoothly through the material. I am addressing something different. I say that that synchronized oscillations within the material organize the material perfectly, so that a current can pass through, or find its way through, the material without any bumps in the road. Thus no friction.

My theory applies to all three superconductors: BCS, pnictide, cuprate. See my other posts, give me a response, and I will respond to you. Space on this site is quite restricted. I appreciate your interest and your comments.
Macksb
1 / 5 (1) Apr 27, 2010
Johan: Some additional points. BCS Cooper pairs are clearly coupled oscillators. Electrons couple by orbit and by spin, both exactly antisynchronous. Pnictides appear to involve synchronized oscillators as a necessary condition, though probably not sufficient. The synchrony is as I describe above; see also a recent PhysOrg article about a Riken announcement, and my comment there. The S + - wave is evidence of synchrony. So too the importance of the exact angle. Other ingredients--probably holes and excitons--are organized by the synchrony and provide the sluiceway through which the current runs smoothly. Cuprates feature d wave symmetry-four lobes. That symmetry is due to synchrony; I believe the lattice vibrations synchronize. That is a necessary condition to create a four way pairing--Pair A antisynch; Pair B antisynch; then Pair AB (2 by 2) antisynch = D wave. Again, holes, excitons are organized in time and space by the synchrony. Huygens pendulum clocks; Art Winfree;antisynch all
johanfprins
1 / 5 (1) Apr 27, 2010
@Macksb,
You still do not understand what I am trying to convey: Namely that a superconductor is an INSULATOR. When a metal goes through a metal-insulator transition it still conducts through hopping caused by temperature fluctuations. Superconduction occurs when these localised states "hop" by means of quantum fluctuations. Cooper pairs (which do not even exist) have NOTHING to do with it. Neither has synchronised oscillations: It has totally to do with Heisenberg's relationship between energy and time: Note that I DID NOT use the term "uncertainty" because Heisenberg's relationships have NOTHING to do with "uncertainties". When will be EVER again be able to become REAL and CAUSAL?
Macksb
1 / 5 (1) May 03, 2010
Johan:

Respectfully, I say the shoe is on the other foot. You reject my comments with the statement that "Superconduction occurs when these localised states hop by means of quantum fluctuations." But quantum fluctuations are a type of limit cycle oscillation (the Winfree requirement). And hopping is a type of limit cycle oscillation. So we appear to have common ground on my point (yours too) that oscillations are critical, despite your protest. As Churchill said of America, we are two peoples separated by a common language.

That leaves the question of synchrony, which I posit but you reject. As to that, Art Winfree demonstrated that limit cycle oscillators have a tendency to synchronize. When they do, the result is usually sudden and non-linear; and the two likely variables are frequency (think temperature, for physics) and proximity (think pressure). Sound familiar?

Synchrony of the medium in time and space paves the way for superconductivity. No bumps, no friction.
johanfprins
not rated yet May 04, 2010
Macksb,
You have a point: We might just be separated by semantics. I am not rejecting that synchronicity can play a role, but only when the density of charge-carriers being injected into a superconductor is high enough. There are then synchronous jumps which approximate wave-front movement. All the charge-carriers on a front jumps simultaneously to replace the next row of charge-carriers etc. Consider sodiers on parade: The back row steps forward to replace the row in front of them whence this row steps forward etc.

The point I am making is that IF such wave-like synchronicity IS required all the time, then a single charge-carrier should not be transported through a superconsuctor. In the case of a single charge-carrier ONE soldier in the back row steps forward, replaces the soldier in front of him which then steps forward etc. It is still a type of synchronicity but it does not invole ALL the charge-carriers as would be the case when the BCS model applies.
Macksb
1 / 5 (1) May 04, 2010
Johan:

I'm mulling over your comments above and in your prior posts.

I envision synchrony as the condition that organizes the medium through which the current travels, whereas your focus is on the current itself. And so your comment about the possibility of wave-like synchronicity focuses on how that might form within the current itself, if it arises at all.

The synchronized medium that I envision in the pnictides arises from perfectly synchronized intersecting waves, leading to S plus minus wave symmetry in time and space. Synchrony begets the symmetry. The image in my mind is an invisible egg carton, with valleys and crests. That in turn organizes the holes and other ingredients of the medium in a manner that allows a current to wend its way through the medium cleanly, finding openings and avoiding obstacles because they are all perfectly organized.

My concept and image are compatible with yours, perhaps, but that question may not be before us at this time.
johanfprins
1 / 5 (1) May 04, 2010
Macksb
I think we are starting to dovetail. Obviously the medium must be "organised" through which the charge-carriers move. For this you require a "metal-insulator" type transition so that the delocalised electron-waves form an array of localised states: Preferably a perfect periodic one. For this your picture of "an invisible egg carton" is very good indeed. These valleys form the anchoring points for the charge-carriers and the crests are the obstacles which the charge-carriers must overcome by means of quantum fluctuations. Have you been to my website? My model is described there in detail as excerpt 23.

Maybe I am misunderstanding you, but my problem with your picture still remains the implication that all the charge-carriers have to move when only a few or a single charge carrier is injected.
Macksb
1 / 5 (1) May 07, 2010
Johan:

Now let me address the movement of the charge carriers, as opposed to the medium through which they move, which is the subject I have addressed in all of my prior posts.

I believe that the charge carriers are synchronized. Not synchronized exclusively unto themselves; but synchronized in a larger system that critically includes the medium itself. Again, I believe that Art Winfree's law of coupled oscillators provides the conceptual and mathematical explanations, albeit in a different context (Art's context was biology, not physics).

My reasoning is straightforward: Superconductivity requires perfection. Synchrony alone provides that perfection. Synchrony in the medium, which I have explained above, must then integrate with the movement of the charge carriers. These two synchronies must be interrelated. This general principle will result in different expressions in different superconductors, since the particular symmetries vary as we know already.
Macksb
1 / 5 (1) May 07, 2010
Johan:

To state it a little differently, the movement of the charge carriers, and the oscillations emanating from the charge carriers, must integrate themselves synchronously into the (already synchronized) medium. This combined synchrony will also be in a recognizable Art Winfree pattern.

Let me describe the seiche created by the angles within the structure. Please refer to my first post, about five above. In a tetragonal structure, this will create an S plus minus wave if there is a perfect intersection of two sets of waves.

In the cuprates, the structure is orthorhombic, as I recall. There, lattice vibrations will produce a 2 by 2 synchrony (like the gait of a horse), which is D wave symmetry. So in cuprates the key oscillations are lattice vibrations; whereas in pnictides (tetragonal) the key oscillations are electromagnetic waves, necessarily in a two way pairing--not two by two, which orthorhombic will produce.

johanfprins
1 / 5 (1) May 08, 2010
Macksb,

Your model demands that ALL the charge-carriers must move simultaneously in synchronicity: This can obviously not be the case when you inject a charges one at a time into a superconductor.

As I have already explained above: The movement has to be a relay race where one charge-carrier replaces the next which etc. In addition this must occur without accelerating the charge-carriers to obtain the kinetic energy required for this movement and without dissipation of this kinetic energy.

The only way in which the latter can happen is by a quantum fluctuation as allowed by Heisenberg's wave relationship for energy and time. Any other mechanism will generate permanent kinetic energy which will then have to dissipate somewhere in the universe. To genertae such kinetic energy ALWAYS requires acceleration and thus a non-zero voltage. Within all superconductors there is no electric-field.

johanfprins
1 / 5 (1) May 08, 2010
Macksb,

Your model gives no reason why the high temperature superconductors are all layered structures. The reason for this is that the charge-carriers responsible for superconduction form between these layers. The electrons are donated by suitable donor-entities within the layers. The electrons between the layers are at a lower energy than they are at the donor sites within the layers. When the density of charge-carriers between the layers reaches a high enough value, superconsuction becomes possible.

In the low temperature metals the array of charge carriers require the metal to go through a metal-insulator transition. An energy gap thus opens up with the charge-carriers within the gap. When the Fermi-level moves into the gap, superconduction initiates at zero activation energy (ae). As the temperature drops the ae increases. This is why the gap increases.

The FULL gap MUST form at the onset of SC or else there will NOT be a jump in heat capacity!

Macksb
1 / 5 (1) May 10, 2010
Johan:

Again, I must disgree, respectfully. You say my model gives no reason why the high temp superconductors are all layered structures. On the contrary, I refer specifically to the structures--orthorhombic in some cases, and tetragonal in others. And I say what happens: lattice vibrations (oscillations) synchronize in orthorhombic structures, and the synchrony produces d wave symmetry, because there must be two, different, two way coupling effects, due to the different lengths of the two arms. The tetragonal structures produce one two way coupling, because the two arms are the same length (not different lengths as in orthorhombic structures). And the two way coupling emerges not from lattice vibrations, in the pnictides, but rather from the intersection of two different sets of electromagnetic waves. So I deal specifically with the structures and the details of the structures. In other posts on the web, I have also dealt with the significance of layers per se.
johanfprins
1 / 5 (1) May 11, 2010
Macksb,

Your reasoning is clever, but it does not explain the following experimental facts:
1. How the electric-field is cancelled at the position of every charge-carrier. If this does not happen, the charge-carriers will be accelerated:
2. How the charge-carriers gain kinetic energy without being accelerated; and
3. What happens to this kinetic energy since it does not dissipate and generate entropy.

These points require that:
1. The charge-carriers must be anchored localised states which polarise to cancel the applied electric-field.
2. To hop from one position to the next, the required kinetic-energy must come from a source, do work so that the hop can occur, and is then returned to the source.

The latter energy-behaviour requires Heisenberg's relationship for energy and time. With every jump of a charge-carrier the energy is borrowed and then returned. If this does not happen it will be thermodynamically impossible to have a perpetual current around a ring.
Macksb
1 / 5 (1) May 24, 2010
The Cornell research on pnictides (Science Daily, 1-20-2010) supports my theory in all respects. Underdoped material studied.

1. "Static, nanoscale lineups of electrons, spanning about 8 times the distance between individual atoms, all aligned along one axis." Confirms my theory: specific spatial arrangements in the medium required.

2. All electrons parallel within one domain; same for another domain; but vertical in one and horizontal in the other. Items 1 and 2 strongly suggest synchronized oscillations, leading to a "basket weave" structure of electrons. Thus oscillations organize electrons--synchrony produces symmetry. Cornell teams says it is like a liquid crystal. Again, same as my theory. Wave sets A and B, 90 degrees.

3. The conduction electrons travel perpendicular to the aligned electrons. Again, same as my theory--symmetry in the medium; conduction electrons distinct and travel in a specific path through perfectly organized medium.

4. More in next post.
Macksb
1 / 5 (1) May 24, 2010
Now I will speculate about the Cooper pairs. Likely to be something other than BCS spherical symmetry. Requirements: paired orbits, and paired spins, either in synch, or antisynch, or one of each. Those two oscillations are exactly antisynchronous in Cooper pairs, but Winfree theory says paired oscillations can also be synchronous (as in kangaroo legs).

So my suggestion: Cooper pairs of A and B electrons, but separated by some distance, with B electron trailing A electron. Orbits synchronised, spins synchronized. I suspect synch, not antisynch. Or same concept, but side by side pairing of A and B electrons, separated, rather than front and back pairing, separated.

This image would be suitable for pnictides and cuprates. Note also that plus and minus format of the synchronized and thus symmetric medium (two way in pnictides, four way in cuprates) would "guide" conduction electrons in their travel, which might be in a straight line or perhaps even in a double helix.
johanfprins
1 / 5 (1) May 24, 2010
@Macksb,
There is a small fact which neither BCS nor your model can explain; and therefore these models cannot explain superconduction. The simple fact is the following: Any conducting material which has "free charges" CANNOT form a superconductor EVEN when these charge-carriers do not scatter or are able to move in synchrony. This fact is high school physics.
When a material has free charges it is physically impossible for a current to flow through it when there is no electric-field EVEN if the charge-carriers experience no impedance whatsoever to their motion.
Zero resistivity is defined by superconduction NOT the other way around! All superconductors has zero scattering of charge-carriers but zero scattering of charge-carriers does NOT mean superconduction. All elephants are mammals but all mammals are not elephants. It is mind-boggling that for nearly 100 years physicists cannot, or do not want to understand this simple incontrovertible logic?
Macksb
1 / 5 (1) May 26, 2010
Let me make another comment about the Cornell research that I describe three posts above. It confirms two other points that I made in prior posts on this site, as follows:

1. I said that the medium in a superconductor should be viewed as a sluiceway, defining the way in which the current flows. The Cornell research shows that the current flows at right angles (orthogally, I estimate) to the alignment of the electrons in the medium. Thus the Cornell current clearly flows in a manner defined precisely by the medium.

2. I also predicted that the current (the conduction electrons) would be synchronized in response to and integrally as a part of the synchrony and symmetry within the medium. In other words, the synchrony within the current would not arise internally within the current, independently of the medium. The two parts, medium and current, must operate in some way as a unit.

When I made those predictions in the posts above, I was unaware of the Cornell research.
johanfprins
1 / 5 (1) May 26, 2010
The two parts, medium and current, must operate in some way as a unit.

In which way? And why is it necessary for ALL the charge-carriers to act as "a unit"?. If you inject just one charge into the superconductor it enters one contact and emerges at the other: Why must ALL the charge-carriers within the superconductor act as a unit when you only have to transfer a SINGLE charge?

Furthermore you do not answer my question: Why does an applied electric-field not accelerate these "sluicegate" charge-carriers? They are free to move and MUST thus be accelerated. And when they accelerate they CANNOT be transferring a supercurrent. With all due respect: This is high school physics: NO material can form a superconducting phase which consist of charge-carriers which can be accelerated: Newton's 2 law prevents such a phase of cancelling an applied electric field while a current is flowing through it; not even if these charge carriers can move in perfect synchronisation as a unit.
Macksb
1 / 5 (1) May 26, 2010
Johan:

Responding to your questions, in order:

1. "In which way": I'm not sure. My general sense is that medium and current must synchronize their interactions, which means in turn that the conduction electrons, in this case, must flow in synchrony with the medium. No bumps, no surprises.

2. Why is it necessary for all charge carriers to act as a unit: I don't say that. I say that medium and current must operate in some way as a unit. The charge carriers themselves do not have to be one monolithic unit, and I do not believe that the charge carriers need even to be a unit unto themselves. I say that medium and current together must be a unit...in some way.

3. Based on your opposition as expressed in many of your various posts, I believe you object to BCS theory itself. Is that the case? Or do you accept BCS theory and thus object only to portions of my theory? That info will help me respond.

Sincerely,

Macksb

johanfprins
1 / 5 (1) May 27, 2010
.... I believe you object to BCS theory itself. .. Or do you accept BCS theory and thus object only to portions of my theory?

I object to all models and theories which cannot give a mechanism how a current can flow WITHOUT ANY ACCELERATION of the charge-carriers. If the charge-carriers are free to move they will, according to Newton's second law be accelerated, whether they do not scatter, move as a unit, move synchronously or in whatever manner. This means that their potential energy will change and one will not be able to measure a zero voltage as Onnes has done. All the models accepted at present fail to explain the simple fact that an applied electric-field is immediately canceller as soon as SC sets in. This is the defining characteristic of superconduction: Zero resistance is a consequence of this cancellation of the electric-field NOT the other way around.
If not so, one would not be able to pour liquid helium! The liq. He should then refuse to fall.
Macksb
1 / 5 (1) Jun 01, 2010
Johan: You are barking up the wrong tree insofar as I am concerned. My theory is mainly outside of your area of focus. To review: I believe that synchrony begets symmetry which begets superconductivity. Art Winfree's law of coupled (read synchronized) oscillators, which he applied only to biology, should also apply to physics. It is rich, powerful and elegant. There are many oscillators that might synchronize, which I have identified. The synchrony (ies) will be in one of many allowable Winfree patterns. The synchrony will produce one or more symmetries in the medium. My focus on the medium is new--not something from BCS theory. Finally, as to the conduction electrons--your main area of interest--I imagine many new forms of pairing, well beyond the spherical symmetry of BCS. Evidence so far indicates two charges, suggesting that there is pairing. If there is pairing, it will be in a Winfree pattern, maybe in a more complex form, responding intelligently to a sluiceway in the medium.
johanfprins
1 / 5 (1) Jun 01, 2010
Macksb, We are talking past each other: Your statement:
I believe that synchrony begets symmetry which begets superconductivity.
does play a role; but does NOT give the primary mechanism responsible for SC.
In fact, my model consists of an array of oscillators which are able to relay charge through the phase in a synchronous manner when the distances between adjacent oscillators become small enough. But this does not explain why they can gain kinetic energy to transport charge AND in addition do not dissipate this energy in any manner to increase entropy within our universe.
As described in section 23 on my website, the latter is only possible by means of Heisenberg's relationship for energy and time. An oscillator can borrow energy to move to, and replace an adjacent oscillator, which does the same. The energy is on loan and is returned before it can dissipate as entropy. Symmetry and synchronicity must be such that the latter mechanism is possible. No pairing is required!
Macksb
1 / 5 (1) Jun 04, 2010
Johan: I'm interested in your analysis of this item. Cornell research "Superconductivity fingerprint found at higher temperatures," August 27, 2009 shows two pictures of crosses--one organized neatly, the other not. Above a certain temp, the neatly organized crosses degenerate into disorganized crosses. When neatly organized, the material (an underdoped cuprate) is superconducting. The neatly organized ones are "in phase" (which to me means synchronized oscillations).

The article says that the crosses are Cooper pairs of electrons. But then the article likens the passage of current to basketballs passed one by one between the crosses.

Questions arise: Then the Cooper pairs are stationary? Are they the medium--not current? And the basketball analogy, taken literally, implies single unpaired charge carriers, which should be of interest to you. The article shows no awareness of these two unusual implications-stationary Coopers and unpaired charge carriers.

Puzzling. Macksb.
johanfprins
1 / 5 (1) Jun 05, 2010
Macksb,
This is exactly the way in which superconduction occurs in ALL superconducting materials: A superconducting phase consists of an array of localised states: Quantum mechanically each state is "an orbital" which is anchored by a positive charge. When the distances between adjacent states become smaller than a critical amount (which in this case gives the "neatly organised crosses), an orbital can borrow energy (delta) E for an allowed time (delta)t to break free and jump to the position of an adjacent orbital; which is replaced and then repeats the process (synchronous jumps): Exactly like basketballs passed from one player to the next. These charge-carriers are NOT Cooper Pairs: NEVER were Cooper Pairs. It is easy to prove from the radiation coming from a Josephson-junction that they are SINGLY charged.
My model predicts which materials can be SC: A pity Bernd Matthias is not around anymore since this was his consistent criticism against BCS; that it has no predictive power.
Skeptic_Heretic
not rated yet Jun 05, 2010
Although formally thinking theorists prefer to see reality homogeneously, the Nature doesn't like sharp boundaries between various models. Whenever possible, it makes smooth transitions between them.
You're insinuating intelligence behind the design. Prove it.
johanfprins
3 / 5 (2) Jun 05, 2010
NisaJ, Alexa, Alizee, Seneca etc. You are becoming boring with your hallucinations. Please go for some help or get some pills; whatever is required!!!
Skeptic_Heretic
not rated yet Jun 05, 2010
LOL, I'm saying instead, Nature keeps no rules.
Well this is demonstrably false.
johanfprins
1 / 5 (1) Jun 06, 2010
You're insinuating intelligence behind the design. Prove it.

Are you insinuating stupidity behind the design? Prove it!
Skeptic_Heretic
not rated yet Jun 06, 2010
You're insinuating intelligence behind the design. Prove it.

Ok show me a known place where you can demonstrate that the known laws of nature no longer exist within their reference frame.