  We report on spin Hall magnetoresistance (SMR) in bilayers composed of Pt and
magnetic insulator MgFe$_{2}$O$_{4}$ (MFO) with spinel structure. The Pt
thickness dependence of the SMR reveals that annealing of the MFO surface
before depositing the Pt layer is crucial for a large SMR with better interface
quality. We also found that oxygen pressure during the MFO growth hardly
affects the SMR while it influences on magnetic property of the MFO film. Our
findings provide important clues to further understanding the spin transport at
interfaces containing magnetic insulators, facilitating development of low
power consumption devices.
