Electronic Structure and Spin-wave Dispersion of Cu2MnAl, Ni2MnSn, and Pd2MnSn Based on Quasi-particle Self-consistent GW Calculations

We calculated spin-wave dispersion of ferromagnetic Heusler alloys; Cu2MnAl, Ni2MnSn, and Pd2MnSn from the dynamical spin susceptibility based on the ground states determined by the quasi-particle self-consistent GW (QSGW) method. Calculated spin-wave dispersions are in good agreement with the experimental neutron scattering data throughout the Brillouin zone in case of Pd2MnSn; however it is overestimated in Cu2MnAl and Ni2MnSn. In the case of Cu2MnAl, overestimation is found only around K points in the Brillouin zone. The calculated spin-wave stiffness constants are close to the experimental values in three alloys. The excellent agreement is due to the better description of the electronic structure of these Heusler alloys by the QSGW compared to the local density approximation. The obtained electronic structure are compared with the experimental spectroscopic data, suggesting that the Mn 3d states are essential for predicting stiffness constant.