Unconventional Field-Like Spin-Torques in CrPt₃

The topological semimetal CrPt₃ has potential for generating unconventional spin torques due to its ferrimagnetic ordering, topological band structure, and high anomalous Hall effect. CrPt₃ exhibits ferrimagnetic behavior only in its chemically ordered phase and is paramagnetic in its chemically disordered phase. By controlling the growth and annealing temperatures epitaxial films of both chemically ordered and disordered phases of CrPt₃ are prepared allowing us to investigate the role of magnetic ordering on unconventional torque generation. We use angle dependent spin-torque ferromagnetic resonance and second harmonic Hall measurements to probe the spin torques generated from epitaxial CrPt₃ in CrPt₃/Cu/Ni₈₁Fe₁₉ heterostructures. With current applied along specific directions with respect to the crystal order we reveal unconventional spin torques in both ordered and disordered films. When current flows parallel to the [11̄1] and [1̄11] directions we observe an unconventional field-like torque that is opposite in sign for the two directions, which lack a mirror plane thus allowing unconventional torques to be generated.