Unconventional Spin Currents in Noncollinear Antiferromagnet Mn₃Ge

Unconventional spin-orbit torque (SOT) has garnered significant attention due to its potential for enabling energy-efficient and deterministic control of magnetization states. Noncollinear antiferromagnets (NCAFs) are considered ideal systems for generating such unconventional SOTs, making them highly promising for the development of next-generation spintronic devices. In this study, we report the generation of spin torques in noncollinear antiferromagnetic Mn₃Ge, revealing the presence of unconventional spin polarizations (specifically, x- and z-polarized spin currents) by employing the spin-torque ferromagnetic resonance (ST-FMR) technique. All-electric SOT switching was successfully demonstrated in a Mn₃Ge-based device with perpendicular magnetic anisotropy (PMA), with a critical current density of 4.2 × 10⁶ A/cm². Furthermore, the device exhibits memristive behavior that effectively emulates the functionality of artificial synapses in convolutional neural networks (CNNs), achieving an accuracy of 92.5% in digital recognition tasks. These results are expected to pave the way toward next-generation fast and energy-efficient memory and neuromorphic computing.