The unidirectional spin Hall and Rashba-Edelstein magnetoresistance is of great fundamental and practical interest, particularly in the context of reading magnetization states in two-terminal spin-orbit torque memory and logic devices due to its unique symmetry. Here, we report large unidirectional spin Hall and Rashba-Edelstein magnetoresistance in a new material family - magnetic insulator/topological insulator Y3Fe5O12/Bi2Se3 bilayers. Such heterostructures exhibit a unidirectional spin Hall and Rashba-Edelstein magnetoresistance that is about an order of magnitude larger than the highest values reported so far in all-metal Ta/Co bilayers. The polarized neutron reflectometry reveals a unique temperature-dependent magnetic intermediary layer at the magnetic insulator-substrate interface and a proximity layer at the magnetic insulator-topological insulator interface. These polarized neutron reflectometry findings echo the magnetoresistance results in a comprehensive physics picture. Finally, we demonstrate a prototype memory device based on a magnetic insulator/topological insulator bilayer, using unidirectional spin Hall and Rashba-Edelstein magnetoresistance for electrical readout of current-induced magnetization switching aided by a small Oersted field.
Bibliographical noteFunding Information:
This work was supported in part by C-SPIN, one of six centers of STARnet, a Semiconductor Research Corporation program, sponsored by MARCO and DARPA. This work was currently being supported in part by SMART, one of the seven centers of nCORE, a Semiconductor Research Corporation program, sponsored by the National Institute of Standards and Technology (NIST) and by the UMN MRSEC program under Award No. DMR-1420013. Parts of this work were carried out in the University of Minnesota Nanofabrication Center, which receives partial support from NSF through NNCI program and in the Penn State Two-Dimensional Crystal Consortium-Materials Innovation Platform (2DCC-MIP) under NSF Grant No. DMR-1539916. The work at CSU was also supported by NSF (Nos. ECCS-1915849; EFMA-1641989). The authors would also like to thank Timothy Peterson for his help on the usage of PPMS. AUTHOR DECLARATIONS Conflicts of Interest The authors have no conflicts to disclose.
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