paper

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

arXiv:1802.07195

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 $2 T$ . Our overall finding extends with Heusler and inverse Heusler alloys, the class of materials that exhibits laser induced magnetic switching.