Why frozen iron-based materials make them both magnetic and superconducting – sciencedaily

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Physicists at the University of Bath in the UK, working with researchers in the US, have discovered a new mechanism by which magnetism and superconductivity coexist in the same material. Until now, scientists could only guess how this unusual coexistence might be possible. The discovery could lead to applications in green energy technologies and in the development of superconducting devices, such as next-generation computer hardware.

Typically, superconductivity (the ability of a material to pass an electric current with perfect efficiency) and magnetism (seen at work in fridge magnets) make poor teammates because the alignment of tiny particles Magnetic electronics in ferro-magnets generally leads to the destruction of the electron pairs responsible for superconductivity. Despite this, the Bath researchers found that the iron-based superconductor RbEuFe4As4, which is superconducting below -236 ° C, exhibits both superconductivity and magnetism below -258 ° C.

David Collomb, a postgraduate physics research student who led the research, explained: “There is a state in some materials where, if you make them really cold – much colder than Antarctica – they become superconducting. . But for this superconductivity to be taken for higher level applications, the material must coexist with magnetic properties. This would allow the development of devices operating on a magnetic principle, such as magnetic memory and computation using magnetic materials, to also benefit of the advantages of superconductivity.

“The problem is that superconductivity is usually lost when magnetism is activated. For many decades scientists have tried to explore a multitude of materials that have both properties in a single material, and materials scientists have recently been successful. to make a handful of such materials.However, until one understands why coexistence is possible, the hunt for these materials cannot be done with such a fine comb.

“This new research gives us a material that has a wide range of temperatures where these phenomena coexist, and it will allow us to study the interaction between magnetism and superconductivity more closely and in great detail. de to identify the mechanism by which this coexistence can occur.

In a study published in Physical examination letters, the team studied the unusual behavior of RbEuFe4As4 by creating magnetic field maps of a superconducting material as the temperature decreased. To their surprise, they found that the vortices (the points in the superconducting material where the magnetic field enters) exhibited a pronounced broadening near the temperature of -258 ° C, indicating a strong suppression of superconductivity as the magnetism subsided. activated.

These observations are in agreement with a theoretical model recently proposed by Dr Alexei Koshelev of the Argonne National Laboratory in the United States. This theory describes the suppression of superconductivity by magnetic fluctuations due to europium (Eu) atoms in crystals. Here, the magnetic direction of each atom of Eu begins to fluctuate and align with the others, as the material drops below a certain temperature. This makes the material magnetic. The Bath researchers conclude that while the superconductivity is significantly weakened by the magnetic effect, it is not completely destroyed.

“This suggests that in our material, magnetism and superconductivity are separated from each other in their own subnets, which interact only minimally,” Mr. Collomb said.

“This work significantly advances our understanding of these rare coexisting phenomena and could lead to possible applications in superconducting devices of the future. It will generate a more in-depth hunt in materials that exhibit both superconductivity and magnetism. applied fields to take some of these materials and turn them into next-generation computing devices.

“I hope that the scientific community will gradually enter an era where we move from researching blue skies to making devices from these materials. In a decade or so, we might see prototypes of devices using this technology that do a real job. “

The American collaborators on this project were the Argonne National Laboratory, Hofstra University and Northwestern University.

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Material provided by University of Bath. Note: Content can be changed for style and length.

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