Spin Hall magnetoresistance (SMR) has been observed in $\mathrm{Pt}/\mathrm{NiO}/{\mathrm{Y}}_3{\mathrm{Fe}}_5{\mathrm{O}}_{12}$ (YIG) heterostructures with characteristics very different from those in $\mathrm{Pt}/\mathrm{YIG}$. This phenomenon indicates that a spin current generated by the spin Hall effect in Pt transmits through the insulating NiO and is reflected from the $\mathrm{NiO}/\mathrm{YIG}$ interface. The SMR in $\mathrm{Pt}/\mathrm{NiO}/\mathrm{YIG}$ shows a strong temperature dependence dominated by effective spin conductance, due to antiferromagnetic magnons and spin fluctuation. Inverted SMR has been observed below a temperature which increases with the NiO thickness, suggesting a spin-flip reflection from the antiferromagnetic NiO exchange coupled with the YIG.

• Received 4 August 2016

DOI:https://doi.org/10.1103/PhysRevLett.118.067202