Impact of the magnetic sublattice configuration on the Spin-Hall Magnetoresistance

Recently, the ferrimagnetic insulating yttrium iron garnet (YIG) has been studied mostly in combination with an adjacent few-nm-thick platinum (Pt) layer. These studies lead to the discovery of a novel spintronic effect, called the spin-Hall magnetoresistance (SMR)[1,2].
Initially, the SMR was studied in the collinear ferrimagnetic insulating YIG, where the SMR was explained by assuming a single magnetic subsystem, which easily aligns with a magnetic field. Later, the SMR was also reported in more complex magnetic insulating systems, such as Gd₃Fe₅O₁₂ (GdIG, canted ferrimagnet)[3] and NiO (anti-ferromagnet)[4]. It was found that each magnetic sublattice contributes separately to the SMR, and it therefor reveals information about the magnetic state of the material.
By comparing the SMR signals from YIG, GdIG and NiO, it is possible to explain the observed differences in behavior. This includes a sign change in the SMR signal, appearing in the canted phase in GdIG, as well as a negative signal (compared to YIG) in all cases for NiO, explained by its magnetic domain structure.

[1]H. Nakayama et al., Phys. Rev. Lett. 110, 206601 (2013)
[2]N. Vlietstra et al., Phys. Rev. B 87, 184421 (2013)
[3]K. Ganzhorn et al., Phys. Rev. B 94, 094401 (2016)
[4]J. Fischer et al., arXiv: 1709.04158 (2017)