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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, we prepare epitaxial films of both chemically ordered and chemically disordered phases of CrPt3, allowing us to investigate the effect 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/Ni81⁢Fe19 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 [1,-1,⁢1] and [-1,1,1] directions, we observe an unconventional fieldlike torque that is opposite in sign for the two directions. Our calculations reveal that this unconventional torque originates from an indirect nonlocal spin-orbit torque due to spin scattering at the CrPt3/Cu interface, in addition to symmetry breaking at this interface. 

Magnetic tunnel junctions (MTJs) with conventional bulk ferromagnets separated by a nonmagnetic insulating layer are key building blocks in spintronics for magnetic sensors and memory. A radically different approach of using atomically-thin van der Waals (vdW) materials in MTJs is expected to boost their figure of merit, the tunneling magnetoresistance (TMR), while relaxing the lattice-matching requirements from the epitaxial growth and supporting high-quality integration of dissimilar materials with atomically-sharp interfaces. We report TMR up to 192% at 10 K in all-vdW Fe3GeTe2/GaSe/Fe3GeTe2 MTJs. Remarkably, instead of the usual insulating spacer, this large TMR is realized with a vdW semiconductor GaSe. Integration of semiconductors into the MTJs offers energy-band-tunability, bias dependence, magnetic proximity effects, and spin-dependent optical-selection rules. We demonstrate that not only the magnitude of the TMR is tuned by the semiconductor thickness but also the TMR sign can be reversed by varying the bias voltages, enabling modulation of highly spin-polarized carriers in vdW semiconductors.