Heat makes electrons spin in magnetic superconductors

Physicists have shown how heat can be exploited for controlling magnetic properties of matter. The finding helps in the development of more efficient mass memories. The result was published yesterday in Physical Review Letters. The international research group behind the breakthrough included Finnish researchers from the University of Jyväskylä and Aalto University.

The ability to control the huge amount of information within the Internet is largely based on the ability to use the of electrons for reading memory devices. The phenomenon is based on the fact that each electron spins in a certain direction. This spin is closely connected with magnetism. Since the 1990s this property has been used for a fast reading of the information in magnetic memories. That is because it was found that the direction of affects the of .

Lately many research groups have aimed at finding a method for using the electric current also to modify the magnetic information, which would make the data writing process much faster than in today's magnetic memories. However, the known methods tend to produce too much . One of the research directions has been to exploit the heat to convert it to a spin current of the electrons, which would then be used for writing the information.

In the research published yesterday the research group showed how heat is converted to in magnetic superconductors. Many metals turn superconducting a few degrees away from the absolute zero of temperature. As a result, the electrical resistivity of the metal vanishes. Magnetic superconductors can be fabricated by placing a superconducting film on top of a magnetic insulator.

Because superconductivity is present only at low temperatures, this phenomenon cannot be directly used in memory applications.

"Our theory is based on superconductivity, but the vanishing resistance is not very essential in it. Because of that the phenomenon could be generalized to other kinds of materials, and possibly such that it would work also at room temperature," explains Prof. Tero Heikkilä from the University of Jyväskylä.

The now published work was theoretical, but the phenomenon has been already found experimentally.

"Our work explained recent experimental results on the seemingly long lifetime of spin in superconductors. The finding resulted from the conversion of heat into spin," explains Dr Pauli Virtanen from the Aalto University.


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More information: "Long-Range Spin Accumulation from Heat Injection in Mesoscopic Superconductors with Zeeman Splitting." Phys. Rev. Lett. 114, 167002 – Published 23 April 2015, DOI: dx.doi.org/10.1103/PhysRevLett.114.167002
Journal information: Physical Review Letters

Provided by Academy of Finland
Citation: Heat makes electrons spin in magnetic superconductors (2015, April 24) retrieved 26 June 2019 from https://phys.org/news/2015-04-electrons-magnetic-superconductors.html
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Apr 24, 2015
A "finding" at the Los Alamos Plasma Research Facility in the late 1980's showed that opposite charges interact at right angles, inducing a spin (described as the 'right hand rule') which prevents the charges from actually vanishing when they interact -- the opposite charges attracting one another but the rotation keeping them apart by centrifugal force, thus establishing a specific wavelength. In a conductor, the spin, and wave motion, is a result of the interaction of the electron's negative charge and the positive charge of the conductor. BTW, this is the same mechanism for the propagation of the dipole photon structure, where the opposite rotating charges give a resultant zero photon charge.

Apr 26, 2015
Actually electrons move at 2/3 the speed of light in a conductor (unless perhaps in a superconductor).

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