  We study spin Hall magnetoresistance (SMR) in Pt/ferrimagnetic insulator
Y$_{3}$Fe$_{5}$O$_{12}$ (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 Gd$_{3}$Ga$_{5}$O$_{12}$ substrate, indicating that the
large SMR can be achieved irrespective to 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 low power consumption spintronic device based on
the magnetic insulator.
