Spin injection from a magnetically near-compensated state in GdFeCo and inverse spin Hall effect in electron–hole compensated metal YH₂

Rare-earth-transition-metal (RE-TM) ferrimagnets are excellent materials for spin encode/decode operations via spin transport in nonmagnetic regions. This superior performance stems from two key factors. First, the antiferromagnetic coupling between RE4f and TM3d sublattices reduces both the spin-transfer-torque switching time and inter-device magnetic-coupling. Second, the RE-TM ferrimagnets function as spin injectors/ejectors, with the TM3d sublattice solely responsible for carrier spin polarization (<i>p</i>), similar to conventional ferromagnetic metals. We performed spin transport experiments using the sign change of<i>p</i>in RE-TM, which exhibits a positive value above the magnetization compensation temperature and a negative value below it. We measured temperature dependencies of the transverse resistances (RT) of electron-hole compensated metal YH₂under out-of-plane spin-polarized current injection/ejection from GdFeCo (Gd:Fe:Co = 25:66:9). The abrupt change in loop polarity of the out-of-plane field dependence ofRTin YH₂between 290 and 300 K, which aligns with the out-of-field curve of the polar Kerr rotation in GdFeCo electrodes, strongly suggests that the observedRTresults from the inverse spin Hall effect (ISHE) in YH₂. We analytically formulated ISHE in terms of the electron and hole spin currents injected from the spin sources, enabling regression analysis to assess the spin transport characteristics of a GdFeCo/YH₂/GdFeCo magnetic double heterostructure. To explain the observed Hall voltages, enhancements in both the spin diffusion length of YH₂and the spin injection efficiency are necessary.