Effects of spin fluctuation on the magnetic anisotropy constant of itinerant electron magnets

TL;DR

This study investigates how spin fluctuations influence magnetic anisotropy in itinerant electron magnets, revealing a universal relation between anisotropy energy and magnetization that aligns with the two-ion anisotropy model.

Contribution

It demonstrates a general relation between magnetic anisotropy and magnetization in itinerant systems, supported by calculations on various alloys and disordered alloys.

Findings

Alloys show K1(T)/K1(0)=(M(T)/M(0))^n with n≈2

Relation supports the two-ion anisotropy model

Universal rule for itinerant electron systems

Abstract

In the disordered local moment picture, we calculated the magnetization (M) and magnetic anisotropy energy (MAE) of FePt, CoPt, and MnAl ordered alloys and body-centered tegragonal FeCo (bct-FeCo) disordered alloy, assuming spatially fluctuated spin configurations at finite temperatures. All alloys exhibit the relation K1(T)/K1(0)=(M(T)/M(0))^n with the exponent (n) around 2. This is consistent with the two-ion anisotropy model, in contrast to the usual single-ion anisotropy model exhibiting n=3. Because these systems have different mechanisms of MAE, we suggest that this relation is a general rule for itinerant electron systems.