Quantification of electronic and magnetoelastic mechanisms of first-order magnetic phase transitions from first principles: application to caloric effects in La(Fe$_x$Si$_{1-x}$)$_{13}$

Eduardo Mendive Tapia; Christopher E. Patrick; Tilmann Hickel; Jörg Neugebauer; Julie B. Staunton

doi:10.1088/2515-7655/acd027

paper

Quantification of electronic and magnetoelastic mechanisms of first-order magnetic phase transitions from first principles: application to caloric effects in La(Fe $_{x}$ Si $_{1 - x}$ ) $_{13}$

arXiv:2302.06484 · doi:10.1088/2515-7655/acd027

Abstract

La(Fe $_{x}$ Si $_{1 - x}$ ) $_{13}$ and derived quaternary compounds are well-known for their giant, tunable, magneto- and barocaloric responses around a first-order paramagnetic-ferromagnetic transition near room temperature with low hysteresis. Remarkably, such a transition shows a large spontaneous volume change together with itinerant electron metamagnetic features. While magnetovolume effects are well-established mechanisms driving first-order transitions, purely electronic sources have a long, subtle history and remain poorly understood. Here we apply a disordered local moment picture to quantify electronic and magnetoelastic effects at finite temperature in La(Fe $_{x}$ Si $_{1 - x}$ ) $_{13}$ from first-principles. We obtain results in very good agreement with experiment and demonstrate that the magnetoelastic coupling, rather than purely electronic mechanisms, drives the first-order character and causes at the same time a huge electronic entropy contribution to the caloric response.

arXiv comment20 pages, 6 figures

Quantification of electronic and magnetoelastic mechanisms of first-order magnetic phase transitions from first principles: application to caloric effects in La(Fex​Si1−x​)13​

Abstract

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Quantification of electronic and magnetoelastic mechanisms of first-order magnetic phase transitions from first principles: application to caloric effects in La(Fe $_{x}$ Si $_{1 - x}$ ) $_{13}$