Enhanced Anomalous Hall Effect in Pt/CoO Heterostructures by Ferrimagnetic Insulator Gating

Interfacial spin current phenomena in multilayer hybrid structures consisting of heavy metal Pt and a ferrimagnetic insulator have recently drawn a great deal of attention. Here, we demonstrate the uncompensated spins of an insulator CoO surface can induce a square anomalous Hall effect (AHE) in a Pt/CoO device, where the AHE will change sign at 200 K for the thickness of CoO t(CoO) = 3.5 nm. More importantly, for a Pt/CoO bilayer grown on ferrimagnetic insulating Y3Fe5O12 (YIG) substrates, the ferrimagnetic gate can enhance the AHE resistance about three times and the Hall sign change temperature can be increased about 100 K compared to that of the Pt/CoO/SiO2/Si sample. Systematic study of the thickness of CoO-dependent AHE of Pt/CoO/YIG heterostructures reveals that the AHE resistance, coercive field, and Hall sign change temperature of Pt/CoO/YIG trilayers reach a maximum at t(CoO) = 3.5 nm. Our results highlight the key role of the antiferromagnetic material in the spin transport behavior of the magnetic multilayer structure, providing a possible pathway to detect the antiferromagnetic moment by electrical measurements, which will be great of importance for antiferromagnetic spintronics.