Magnetism-dependent phonons and its effect on magnetic phase transition from first principles

Magnetism-dependent phonons in ferromagnetic materials have been found even in simple magnetic materials such as bcc Fe. Although this phenomenon was recognized, its influences on equilibrium magnetic states have been overlooked. In this presentation, we introduce the impact of the magnetism-dependent phonon on the magnetic phase transition and the electronic origin of the dependence. The magnetism-dependent phonons stabilize magnetically disordered states, and thereby the Curie temperature is also influenced [1]. Additionally, our first-principles phonon calculations considering magnetically disordered states reveal a clear relationship between the degree of dependence and crystal symmetry [2]. We explain the origin of the relationship by introducing a concept, exchange ligand field.

[1] T. Tanaka and Y. Gohda, arXiv:2006.02604.
[2] T. Tanaka and Y. Gohda, J. Phys. Soc. Jpn. 89, 093705 (2020).