Spin Hall magnetoresistance at the altermagnetic insulator/Pt interface

Spin Hall magnetoresistance (SMR) describes how the resistivity of a heavy metal is modulated by the proximity of a magnetic material. In this work, the authors demonstrate SMR at the interface between platinum and an insulating ferroelectric altermagnetic candidate, Ba₂CoGe₂O₇ -- an emerging class of collinear compensated magnets with unique combined spin and crystal symmetries. They show that this heterostructure exhibits a relatively large SMR signal regardless of the unoptimized interface between bulk BCGO and Pt. Furthermore, the SMR is anisotropic with the crystal orientation of the current. Possible contributions, including the role of altermagnetism or ferroelectricity, are discussed. The results show a possible route towards tunable and electrically controllable SMR responses in spintronic devices.