Ultrafast magnetization dynamics in pure and doped Heusler and inverse Heusler alloys

TL;DR

This study uses first-principles and spin dynamics to explore ultrafast magnetization switching in pure and doped Heusler alloys, revealing rapid switching capabilities and unique damping behavior related to their electronic structure.

Contribution

It introduces a multiscale approach combining density functional theory and atomistic spin dynamics to analyze magnetization dynamics in doped Heusler alloys, highlighting their ultrafast switching potential.

Findings

Rapid magnetization switching at threshold fields of 2T.

Doping reduces damping in inverse Mn2CoAl alloys.

Short-range exchange interactions due to electronic band gaps.

Abstract

By using a multiscale approach based on first-principles density functional theory combined with atomistic spin dynamics, we investigate the electronic structure and magnetization dynamics of an inverse Heusler and a Heusler compound and their alloys, i. e. Mn$_{2-x}Z_x$CoAl and Mn$_{2-x}Z_x$VAl, where $Z$ = Mo, W, Os and Ru, respectively. A signature of the ferrimagnetic ordering of Mn$_{2}$CoAl and Mn$_{2}$VAl Heusler alloys is reflected in the calculated Heisenberg exchange constants. They decay very rapidly with the interatomic distance and have short range, which is a consequence of the existence of the finite gap in the minority spin band. The calculated Gilbert damping parameter of both Mn$_2$CoAl and Mn$_2$VAl is high compared to other half-metals, but interestingly in the particular case of the inverse Mn$_{2}$CoAl alloys and due to the spin-gapless semiconducting property, the damping parameters decrease with the doping concentration in clear contradiction to the general trend. Atomistic spin dynamics simulations predict ultrafast magnetisation switching in Mn$_{2}$CoAl and Mn$_{2}$VAl under the influence of an external magnetic field, starting from a threshold field of $2\text{T}$. Our overall finding extends with Heusler and inverse Heusler alloys, the class of materials that exhibits laser induced magnetic switching.