Tunneling magnetoresistance and spin-orbit torque magnetization switching in ferrimagnetic Gd-Fe-Co based magnetic tunnel junction

Spin-orbit torque magnetization switching is studied in three-terminal magnetic tunnel junctions with a ferrimagnetic Gd-Fe-Co free layer. Pt is used as a spin current generation layer and a Co-Fe-B synthetic antiferromagnet is used as the reference layer. A thin Fe-B layer is inserted between the Gd-Fe-Co free layer and the MgO barrier. The thickness of the Fe-B layer is varied from 4 to 12 & Aring;. We find the tunnel magnetoresistance ratio increases with increasing Fe-B layer thickness until it saturates at similar to 14%, while the current density needed to reverse the magnetization of the Gd-Fe-Co/Fe-B layer via spin-orbit torque remains almost unchanged. The results highlight the effectiveness of the thin Fe-B layer in obtaining sizable tunneling magnetoresistance and efficient spin-orbit-torque switching.