Effective tight-binding model of compensated ferrimagnetic Weyl semimetal and analysis of spin-orbit torque*

Magnetic Weyl semimetals (MWSMs) are new states of matter and have nontrivial gapless nodes (Weyl points) in the bulk band. The Weyl points correspond to sinks or sources of Berry curvature in momentum space and give rise to the novel magnetoelectric phenomena. A variety of materials such as Co₃Sn₂S₂ and Mn₃Sn have been identified as MWSMs due to crystalline and magnetic structure. In 2018, an inverse Heusler compound Ti₂MnAl with compensated ferrimagnetic ordering was discovered as a candidate for MWSMs [1] by first-principles calculations. In this talk, we propose a low-energy effective tight-binding model of Ti₂MnAl. We calculate the electronic structure near the Fermi level and the anomalous Hall conductivities (AHCs). Furthermore, we found that finite spontaneous orbital magnetization appears at the energy of Weyl points. In addition, we suggested that the magnetic moment of each site is correlated with the direction of the orbital magnetization and AHCs, which can be manipulated by an external field [2].

We will also discuss the spin-orbit torques in Ti₂MnAl using our model. We expect that current-induced spin torques, including the spin-orbit torques, will provide an alternative way to manipulate spin dynamics without using external magnetic fields.

[1] W. Shi, L. Muechler, K. Manna, Y. Zhang, K. Koepernik, R. Car, J. van den Brink, C. Felser, and Y.Sun, Phys. Rev. B 97, 060406 (2018)

[2] T. Meguro, A. Ozawa, K. Kobayashi, K. Nomura, arXiv:2304.14009 (2023)