Fig. 2: Device schematics and magnetoresistance.
a Schematic of easy-plane spin Hall oscillator (EP-SHO) based on a heavy metal (HM=Pt) and a ferromagnetic metal (FM=Co∣Ni superlattice) bilayer nanowire, as well as the Cartesian (x, y, z) and spherical (ϕ, θ) coordinate systems used here. A positive direct charge current in the HM layer + Idc (black dashed arrow) generates a spin Hall current js (gray dashed arrow) flowing in the z-direction with its polarization in the −y-direction (green arrows). Spin current js impinging on the FM applies spin Hall torque τst to magnetization M and pulls it out of the easy xz-plane. The magnetization then precesses about the easy-plane anisotropy field Ha∣∣y as indicated by black arrows. b Scanning electron micrograph of an EP-SHO. The scale bar is 100 nm. c Resistance of the EP-SHO device in b as a function of a 4 kOe (400 mT) magnetic field direction in the xy-plane measured at T = 4.2 K.
