Spin Orbit Torques from Magnetically Ordered Topological Semimetal CrPt₃

Spin-orbit effects in some magnetically ordered materials have been shown to produce large spin torques with exotic geometries defined by the magnetic ordering of the material. In such materials, it may be possible to modify the magnetic ordering in order to optimize the geometry of the produced torques for applications to novel computing technologies including magnetic random access memory and neuromorphic computing. CrPt₃ is a topological semimetal [1] that offers a promising system for probing these effects, both for its large spin-orbit effects, large intrinsic Hall effect and its magnetic ordering with tunable anistropy. CrPt₃ shows ferrimagnetic behavior when chemically ordered, but paramagnetic behavior when disordered [2]. Thus, it is possible to compare CrPt₃ grown in each state and examine the role of magnetic ordering in its spin current generation properties. We present angular-dependent and DC biased spin torque ferromagnetic resonance measurements characterizing the size and geometry of spin currents generated in epitaxial CrPt₃ films. We additionally probe the dependence of the ordering direction on the resulting spin torques. Finally, we examine the effects of variation in the magnetic ordering on the generated spin currents.

[1]. A. Markou et al, Comm. Phys. 4, 104 (2021).

[2] O. Hellwig et al., Appl. Phys. Lett. 79, 1151 (2001).