Researchers seeking the fourth property of electrons

Jul 20, 2010
Juelich researchers want to demonstrate the electric dipole moment of the electron in cooperation with colleagues in the USA and the Czech Republic. Many physical theories presume its existence -- for example, some theories concerning the creation of the universe. In order to improve the precision of previous measurements, they have created a new ceramic material with the aid of the Juelich supercomputer JUROPA. Credit: Forschungszentrum Juelich

Do electrons have a fourth property in addition to mass, charge and spin, as popular physics theories such as supersymmetry predict? Researchers from Germany, the Czech Republic and the USA want to find the answer to this fundamental question of physics. In order to improve the precision of previous measurements, they have created a new material with the aid of the Juelich supercomputer JUROPA. The scientists report on this in the current issue of Nature Materials.

Electrons are negatively charged elementary particles. They form the shells around atoms and . This or something similar is what you will find in text books. Soon, however, this information may have to be supplemented. The reason is that many physicists believe that electrons have a permanent electric dipole moment. An electric dipole moment is usually created when positive and negative charges are spatially separated.

Similar to the north and south poles of a magnet, there are two electric poles. In the case of electrons, the situation is much more complicated because electrons should not actually have any spatial dimension. Despite this, an entire range of physical theories that go beyond the of elementary particle physics are based upon the existence of dipole moment. These theories in turn would explain how the universe in the form that we know it could have been created in the first place. According to prevailing theories, the some 13.7 billion years ago would have had to have created just as much matter as antimatter. Since both obliterate each other, nothing would have remained. In reality, however, more matter than was actually created. An electric dipole moment of the electron could explain this imbalance.

Up to now, nobody has successfully proven the existence of this assumed tiny dipole moment. Existing methods are simply not sensitive enough. A small piece of ceramic is set to change this soon. Dr. Marjana Ležaić and Dr. Konstantin Rushchanskii from the Institute of Solid State Physics at Forschungszentrum Jülich and Professor Nicola Spaldin from the University of California in Santa Barbara designed this ceramic, which has very special properties, in a virtual laboratory using the Jülich JUROPA. The new europium barium titanate should enable measurements to be 10 times more sensitive than they were in the past. According to the Julich physicists, "this could be sufficient to find the electric dipole moment of the electron".

As electric moment cannot be directly measured, the physicists are working together with scientists from the American Yale University as well as with Czech research institutions in Prague in order to indirectly prove its existence. The researchers in Yale have developed an experimental setup that uses an extremely sensitive SQUID magnetometer to measure the magnetization of the piece of ceramic in an electric field. Their aim is to demonstrate a change in the magnetization when the electric field is reversed. This would simultaneously be the sought-after evidence that the electric dipole moment exists. In an electron, an electric dipole can only ever be oriented parallel or anti-parallel to the electron spin. In an electric field, most of the electrons are oriented so that their dipole moment is parallel to the field. Fewer are oriented in the other direction. This should lead to a measurable magnetization. If the is reversed, the dipole moments of the electrons are reversed leading consequently to a simultaneous, measurable change in the magnetization. Without an electric dipole moment, on the other hand, the magnetization would remain unchanged.

"It would have been very difficult to find such a well-suited material by trial and error," said Ležaić. This material must have an unusual combination of properties: a high concentration of magnetic ions, magnetic disorder at temperatures below four degrees Kelvin and a reversible electric polarization. "Our colleagues in Yale who came up with the idea of the measurements and conducted them had already tested different materials. However, a new material with all of the necessary properties can be found faster with the use of theoretical analysis and computer simulations." Ležaić, as the head of the young investigators group, her group member Rushchanskii, and her cooperation partner Spaldin virtually synthesized and analysed europium barium titanate on the supercomputer in Julich. To do so, all they needed was its chemical composition and the basic equations of quantum mechanics. From these, they calculated the interaction between individual atoms and and the local magnetic properties. So it was that they found the optimum ceramic.

Team colleagues in Prague have already synthesized and characterized the material in the laboratory and confirmed the properties calculated in Julich. Only the sought-after dipole moment of the electron remains undiscovered. "Unwanted effects are still inhibiting the measurements," said a disappointed Ležaić. "But we're working intensively on improving the material even further."

Explore further: Guidelines for enhancing solar cells using surface plasmon polaritons

More information: A multiferroic material to search for the permanent electric dipole moment of the electron; DOI: 10.1038/NMAT2799

Related Stories

Shielding for ambitious neutron experiment

Jul 24, 2008

In science fiction stories it is either the inexhaustible energy source of the future or a superweapon of galactic magnitude: antimaterial. In fact, antimaterial can neither be found on Earth nor in space, is extremely complex ...

Electric control of aligned spins improves computer memory

Jan 19, 2010

Researchers from Helmholtz-Zentrum Berlin (HZB, Germany) and the French research facility CNRS, south of Paris, are using electric fields to manipulate the property of electrons known as "spin" to store data permanently. ...

Making magnetic monopoles, and other exotica, in the lab

Feb 05, 2009

Physicist Shou-Cheng Zhang has proposed a way to physically realize the magnetic monopole. In a paper published online in the January 29 issue of Science Express, Zhang and post-doctoral collaborator Xiao-Liang ...

Spin-polarized electrons on demand

Jan 21, 2009

Many hopes are pinned on spintronics. In the future it could replace electronics, which in the race to produce increasingly rapid computer components, must at sometime reach its limits. Different from electronics, where whole ...

Spin-polarized electrons on demand

Jan 15, 2009

Many hopes are pinned on spintronics. In the future it could replace electronics, which in the race to produce increasingly rapid computer components, must at sometime reach its limits. Different from electronics, where whole ...

Recommended for you

User comments : 28

Adjust slider to filter visible comments by rank

Display comments: newest first

El_Nose
4 / 5 (4) Jul 20, 2010
Now that is science -- makes me proud to be human that does.
Jigga
1.8 / 5 (5) Jul 20, 2010
The existence of a nonzero electron electric dipole moment would imply a violation of both parity invariance and time reversal invariance. The most recent experiment performed at the University of California at Berkeley placed an upper bound on (with a 90% confidence level) of |de| < 1.6.10E-27 e.cm, whereas supersymmetric models predict that |de| < 10E-26 e.cm - the present experimental limit is therefore close to eliminating these theories, too.

http://dx.doi.org...8.071805
Bonkers
5 / 5 (1) Jul 20, 2010
Good post. Can i presume you mean that supersymmetric models predict greater than 10E-26 e.cm and thus may soon be eliminated.
Any details on this would be interesting, is it possible for instance that the (inherently) spatial dipole moment might be in one of the "other" 6 directions?
Husky
4 / 5 (1) Jul 20, 2010
it might be usefull to use muons as well as they are the heavyweight brother of electrons in terms of mass, perhaps they exhibit a more measurable dipole moment as well
Jigga
1.7 / 5 (6) Jul 20, 2010
Skeptic_Heretic
3 / 5 (4) Jul 20, 2010
The existence of a nonzero electron electric dipole moment would imply a violation of both parity invariance and time reversal invariance.

How exactly would that be either a parity invariance or a time reversal invariance?
axemaster
not rated yet Jul 20, 2010
I seriously doubt the existence of this dipole moment, for the same reason that I doubt they'll ever find magnetic monopoles - they are theories without any geometric analogy whatsoever, in a universe where everything we've ever observed is produced - and predicted - geometrically.
Skeptic_Heretic
3 / 5 (4) Jul 21, 2010
How exactly would that be either a parity invariance or a time reversal invariance?

It's explained here http://www.tinyurl.cz/v0k

How about a specific citation. I don't want to re-read several hundred pages to attempt to tease your poor understanding of the material out of its pages.
otto1923
3.3 / 5 (3) Jul 21, 2010
I seriously doubt the existence of this dipole moment, for the same reason that I doubt they'll ever find magnetic monopoles - they are theories without any geometric analogy whatsoever, in a universe where everything we've ever observed is produced - and predicted - geometrically.
What about entanglement- there's no analogy for that.
Skeptic_Heretic
3 / 5 (2) Jul 21, 2010
However, since d is a vector, its expectation value in a state |phi> it must be proportional to . Thus, under time reversal, an invariant state must have vanishing EDM. In other words, a non-vanishing EDM signals both P and T symmetry-breaking.
By your logic above one must induce a time reversal invariant in order to create parity invariance. You're breaking the equation intentionally, not through objective analysis.
otto1923
3.7 / 5 (3) Jul 21, 2010
What about entanglement- there's no analogy for that.
Of course they exist http://www.tinyurl.cz/v10
No I mean really-
Skeptic_Heretic
3.4 / 5 (5) Jul 21, 2010
Frankly, you can't mean anything, because you don't understand it
You're breaking the equation intentionally, not through objective analysis.

Editing system broke this equation, not me.

Nice ad hominem attack, baseless as usual. And you're breaking the equation in your use of it, not your reposting of it.
Donutz
Jul 21, 2010
This comment has been removed by a moderator.
frajo
4 / 5 (5) Jul 21, 2010
He's right about the editing system, though. Sucks.
If one cannot use it then why do some people try to use it nevertheless?
Jigga
2.7 / 5 (7) Jul 21, 2010
..If one cannot use it then why do some people try to use it nevertheless?

Because they cannot use another one? Just a random guess..
Skeptic_Heretic
2.6 / 5 (5) Jul 21, 2010
..If one cannot use it then why do some people try to use it nevertheless?

Because they cannot use another one? Just a random guess..

Banned from that many science forums now? Perhaps if you stuck to the one screen name and didn't post garbage you wouldn't be in this situation.
Hesperos
not rated yet Jul 21, 2010
"To do so, all they needed was its chemical composition and the basic equations of quantum mechanics. From these, they calculated the interaction between individual atoms and electrons and the local magnetic properties."

That's more impressive to me than the ceramic!
Gawad
4.2 / 5 (5) Jul 22, 2010
...the core of electron...center of electron mass...energy is concentrated here....the second loop is revolving this first one at the distance of 10E-15 m or so. In addition, electron is a textbook example of supersymmetry, too. It's a composite artifact of transverse and longitudinal waves of energy, which are interfering mutually. From this perspective, electron orbitals are tiny dark matter clouds, surrounding the atom nuclei in extra-dimensions....foam...internal walls...analogy of electron at human society...ability to reconcile intrinsic and extrinsic perspectives with apparent conflict of interest...undulating between perspectives.


Over the years I've read some really wild stuff get posted on physorg. I've never said a word, but really now I simply must know. AlizeeEtc, this stuff...the stuff you're on...WHAT IS IT? Can your dealer ship internationally? Does it have to be taken intravenously or can it taken another way(I don't want to have to deal with needles)? Thnks!
solidspin
4 / 5 (4) Jul 23, 2010
@ Jigga, et al.

CPT violations are fine. The electron, under a time-reversal operator, simply rotates by i - so no parity invariance, just time. This is known and you can do it via matrices and applying the time-reversal operator to a Pauli matrix - we proved it in my Sol-state Phy grad class.

It's interesting that it may have a net dipole moment because it is an elementary particle - a lepton - and therefore never found to have had internal structure.
Gawad
4.3 / 5 (6) Jul 23, 2010
Internal structure of electron was revealed by inelastic collisions in HERA experiment at DESY already. [Crackpot assertions deleated].

http://physicswor...ws/22707


Along your imaginary axis, certainly. Aside from that, there is no indication either quarks or leptons have any internal structure. (Well, o.k., some experiments with electons in ultracold helium have suggested it might be possible to seperate an electron waveform spatially, but even that wouldn't indicate *internal* structure.)

BTW, as usual the article you link to has nothing to do with the topic you raise : the internal structure of the electron (except in your cranky imagination). The article doesn't discuss this, doesn't bring it up, doesn't even mention it.

For, years I've consulted physorg for breaking news on science and nearly every bloody physics thread becomes POISONED with your nonsense. It just never ends. Obsessive-compulsive much? Get treatment for goodness sake!
Gawad
3.4 / 5 (5) Jul 23, 2010
No. The article you link to IS "classical physics" (I presume you mean classic physics). But your trying to make your notion of internal electron structure seem "classical" as well by unjustly tying it to that article is just CRANKY. That article has nothing to say about electron structure. Once again, doesn't deal with it, doesn't bring it up, and gives it not even a mention. The only thing it really does is confirm the electron couples to the Weak field. Not exactly a surprise (but outstanding high precision work).

And the photon is supposed to be a "blob with 3 distinct regions"? Just a given, huh? Please, no links. Don't bother. I can only imagine 3 reasons for such pseudo-scientific BS:

* One hell of a wicked acid trip
* Organic brain damage
* Obsessive-compulsive trolling

I can't even reliably filter out your posts anymore because your BAD HABITS have even messed up that safeguard.

So whatever it is, get help. We'll all be better off for it. You most of all!
Jigga
1.7 / 5 (6) Jul 23, 2010
BTW if mass is additive, then every electron should maintain a layer of dark matter around itself, too. Such layer extends visible matter at megaparsec scale - which means, it must be formed by a field, which is spreading pretty fast.
frajo
3.4 / 5 (5) Jul 24, 2010
He's right about the editing system, though. Sucks.
If one cannot use it then why do some people try to use it nevertheless?
This one was voted on by Jigga and by VestaR which - as we all know - are two accounts of the same cheater.
sender
1 / 5 (2) Jul 25, 2010
http://www.physor...122.html

Maybe plasmaron physics can answer the question of electron dipole movements.
Skeptic_Heretic
2.3 / 5 (3) Jul 25, 2010
BTW if mass is additive, then every electron should maintain a layer of dark matter around itself, too. Such layer extends visible matter at megaparsec scale - which means, it must be formed by a field, which is spreading pretty fast.

Would depend on the charge or interaction between the two particles. As for the field, that would be gravity, or so the theorists say.
frajo
3 / 5 (4) Jul 26, 2010
Would depend on the charge or interaction between the two particles. As for the field, that would be gravity, or so the theorists say.
And again, the cheater Jigga/VestaR has rated a comment twice.
I don't understand why the PhysOrg administration doesn't stop this kind of poisoning the comment system.
Skeptic_Heretic
3.4 / 5 (5) Jul 26, 2010
Dark matter field is not a gravity field and it extends gravity field in many orders of magnitude. After all, this is why we can observe it by gravitational lensing outside of galactic clusters.
The only observed interaction with dark matter is gravitationally. There are no other forces or fields at play according to all known observations.
Nobody prohibits you in voting on per-peer basis (as you're doing) instead of per-post basis - which is the abuse of the same category - it leads into bias of result and into establishing of voting mafia. In my opinion whole voting system is useless, because it can be abused easily in uncontrolled way.

The only abuse is when a single individual receives more than one vote through having more than one screen name, as you do and have done above.
Skeptic_Heretic
3.4 / 5 (5) Jul 26, 2010
Just face the reality - you cannot fight against abusing of voting system with using of another abuse of it.
I have no need to fight anything. Simply exposing your actions is enough to invalidate their effect and that's the last I have to say on the topic.
Skultch
3 / 5 (2) Jul 27, 2010
VestaR/Jigga/Alizee is a bot. That's my theory. Some bored grad student with access to a super computer is performing the Turing test on us. There! I just figured you out. Back to the drawing board. :)