Spin Hall magnetoresistance in Pt/Y3Fe5O12 bilayers grown on Si and Gd3Ga5O12 substrates

We study spin Hall magnetoresistance (SMR) in Pt/ferrimagnetic insulator Y3Fe5O12 (YIG) bilayers by focusing on crystallinity, magnetization, and interface roughness by controlling post-annealing temperatures. The SMR in the Pt/YIG grown on Si substrate is comparable to that grown on widely used Gd3Ga5O12 substrate, indicating that the large SMR can be achieved irrespective of the crystallinity. We deduced the spin mixing conductance from the Pt thickness dependence of the SMR to find the high interface quality of the optimized Pt/YIG grown on Si in terms of spin current. We also clarified that the SMR correlates well with the magnetization, the interface roughness, and carrier density. These findings highlight that optimizing YIG properties is a key to control of magnetization by spin current, leading to the development of the low power consumption spintronic device based on the magnetic insulator.