What is it about?
Magnets lose their magnetization when heated to their Curie point, where there is usually a sharp but continuous decline of magnetization to zero (2nd order transition). In some cases the transition is discontinuous and occurs at a different temperature on heating or cooling (1st order transition). We have found that that the order of the transition can be tuned by small alloy additions in a new class of topological ferromagnetic metals.
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Why is it important?
A potential application of ferromagnets is for magnetic refrigeration. Our work provides new insight into how to choose an optimum magnetic material for this purpose.
Perspectives
It was surprising to find that the textbook magnetic phase transition could be influenced by the topology of the spin-dependent electronic structure in a ferromagnetic metal. It was close collaboration with an expert in topology for physicists and our detailed experimental investigation of the critical behavior of three closely-related pyrite materials that convinced us that this really is the case. It was a bonus that the finding may have a practical. benefit, in magnetic refrigeration.
Michael Coey
School of Physics, Trinity Colllege, Dublin, Ireland
Read the Original
This page is a summary of: Influence of topology on the phase transition of a ferromagnetic metal, Proceedings of the National Academy of Sciences, August 2023, Proceedings of the National Academy of Sciences,
DOI: 10.1073/pnas.2302466120.
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