CeCoIn5 reveals new secrets about how superconductivity and magnetism can be related

Jan 06, 2014
Simon Gerber, first author of the publication on the superconducting properties of CeCoIn5 at the Morpheus instrument of the Spallation Neutron Source SINQ in Switzerland. Credit: Paul Scherrer Institute/Markus Fischer

(Phys.org) —Superconducting materials exhibit unexpected behaviors when subjected to magnetic fields or high pressures –discoveries that have implications for controlling electrons in those special materials. According to two studies, one conducted at the Paul Scherrer Institute in Switzerland with collaborators at Los Alamos National Laboratory and a second at Los Alamos in collaboration with the Sungkyunkwan University in South Korea, the superconducting material Cerium-Cobalt-Indium5 reveals new secrets about how superconductivity and magnetism can be related.

Superconductivity and magnetism are normally seen as rivals – superconducting and magnetic order themselves in very different ways. Like spinning tops, electrons in superconductors form pairs of tops, one spinning counterclockwise and one spinning clockwise. Together, these pairs move freely to conduct electrical current with zero resistance. Magnetic electrons, in contrast, lock themselves into a rigid arrangement that does not move. Two papers recently published in the journal Nature Physics show that electrons in Cerium-Cobalt-Indium5 are both superconducting and magnetic at the same time.

In an experiment conducted at the Paul Scherrer Institute, researchers observed an entirely new form of superconductivity, one in which electrons form pairs with spinning tops moving clockwise and counterclockwise as well as pairs spinning in the same direction. This surprising new form of superconductivity appeared only when electrons were both superconducting and magnetic. As these researchers showed, the ordered arrangement of the magnetic electrons can be manipulated by modifying the direction of an applied magnetic field.

"The observed behavior of the material was completely unexpected and is certainly not a purely magnetic effect" explains Michel Kenzelmann, head of the PSI research team. "This is a clear indication that in the material the new superconducting state occurs together with the spin density wave."

These findings indicate the possibility of direct control of the quantum state of electrons which is linked to superconductivity. The possibility of directly controlling quantum states may be important for possible future quantum computers.

Another study on CeCoIn5 also observed unexpected behavior. When small amounts of impurities were introduced into this material, superconducting electrons formed nano-droplets of magnetic order. As more impurities were added, the droplets grew and eventually overlapped causing the entire material to become magnetic. Applying pressure to the magnetic material globally reversed the effect of adding impurities and Cerium-Cobalt-Indium5 became superconducting again. Using a technique like magnetic resonance imagining (MRI), the researchers found, however, that nano-droplets of magnetic order remained but were hidden by the superconductivity. In effect, electrons in CeCoIn5 acted like an oil-vinegar salad dressing, with superconducting electrons playing the role of oil and magnetic electrons the role of vinegar.

These studies of superconductivity in Cerium-Cobalt-Indium5 have shown that electrons are more adaptable than previously supposed. They can form a salad-dressing like state, which may be important for understanding properties of materials that until now have been mysterious, and they can pair simultaneously in two different configurations when they coexist with .

"Superconductivity continues to give new surprises. As its secrets are revealed, we learn more about the quantum world of electrons and can begin to imagine new ways to use them for future technologies. Superconductivity in Cerium-Cobalt-Indium5, discovered nearly a decade ago at Los Alamos, may be the Rosetta Stone that many of us have been looking for" says Joe Thompson, a collaborator in both studies.

The papers "Switching of magnetic domains reveals spatially inhomogeneous " and "Disorder in quantum critical superconductors" appeared back-to-back in the December 22, 2013 advanced on-line issue of Nature Physics.

Explore further: Superconductivity switched on by magnetic field

More information: "Switching of magnetic domains reveals spatially inhomogeneous superconductivity." Simon Gerber, Marek Bartkowiak, Jorge L. Gavilano, Eric Ressouche, Nikola Egetenmeyer, Christof Niedermayer, Andrea D. Bianchi, Roman Movshovich, Eric D. Bauer, Joe D. Thompson & Michel Kenzelmann. Nature Physics (2013). DOI: 10.1038/nphys2833

"Disorder in quantum critical superconductors." S. Seo, Xin Lu, J-X. Zhu, R. R. Urbano, N. Curro, E. D. Bauer, V. A. Sidorov, L. D. Pham, Tuson Park, Z. Fisk & J. D. Thompson. Nature Physics (2013) DOI: 10.1038/nphys2820

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KBK
4.5 / 5 (2) Jan 06, 2014
The false enforced environment of lowered temperature allows for two geometric polarized locking states, not one.

The next step is to find origins , via raising the temperature bit by bit, and performing the same experiments and looking at the ratio of superconducting vs magnetic electrons.

Since it will turn out to be a energetic locking issue, geometric alignment/polarized... that is based on resonance and elasticity, as Maxwell stated..then we will find that room temperature superconductivity is going to have aspects of such a nature.

The 'problem' is one of the 'noise' levels of what we call 'normal human life, ie elevated temperatures but still allowing for stability.

What we will find is that we will have AC superconductors, not DC superconductors. The only way to have 'room temp' superconductors, at this time in our understanding of things, is to make a 'semi-superconductor' that is AC in nature. If off resonance, no superconductivity -it works only at resonance.
KBK
2 / 5 (1) Jan 06, 2014
It will also produce secondary issues, like dimensional gating, so, well, have fun - but be careful, be advised.

Obviously, there's the "over-unity" fundamental that the alternative crowd has found to be so real.
Macksb
5 / 5 (2) Jan 06, 2014
These "surprises" are consistent with Art Winfree's law of coupled periodic oscillators, which he first described circa 1967, and my many prior posts applying Winfree's law to physics, most often to superconductivity.

The article (first half) describes two forms: anti-synchronous ("clockwise and counterclockwise") and, surprisingly, synchronous ("pairs spinning in the same direction"). In many prior posts, I have proposed that Winfree's law underlies superconductivity in all its forms; and further, that two oscillator systems, of which Cooper pairs are an example, can couple in two ways, pursuant to Winfree's law: either exactly anti-synchronous, or exactly synchronous. Bingo.

Winfree's law is well described by Steve Strogatz and Ian Stewart: Coupled Oscillators and Biological Synchronization, Sci. American, December 1993. Thoroughly vetted by mathematicians; pervasive in biological systems; but ignored by physicists. Yet physics is rife with periodic oscillations.
EWH
5 / 5 (2) Jan 23, 2014
Interesting idea. Both Winfree's systems and quantum mechanics are mostly the result of relative phases between populstions of oscillators. The SIAM obit for Winfree is worth reading.

In applying Winfree's ideas to electrons, Hestene's formulation of zitterbewegung is the most fundamental and geometric type of oscillation. Zitterbewegung is a helical, light-speed motion of a point charge around its average path with a frequency of 1.6E21 Hz.. The orientation of the helix is the electron spin, the curvature of the helix is the electron mass, the angle of the particle around the helix is the electron phase, and the helical motion creates a static magnetic dipole and a rotating electric dipole. This is best expressed in a (1,3) signature Clifford / Geometric algebra with the helices being null paths. Statistical populations of these oscillators which become coupled must act similarly to the systems Winfree studied.

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