Strain-Induced Interlayer Parallel-to-Antiparallel Magnetic Transitions of Twisted Bilayers

Abstract

The discovery of superconductivity in twisted graphene bilayers with a magic twisting angle ≈1.1° has opened up a wide range of potential twistronic device possibilities. In this work, the twisting effects in spintronic devices are explored. In particular, a material prototype integrating spintronics, straintronics, and twistronics is developed by stacking a twisted CoFe2O4 (CFO) bilayer membrane on a Pb(Mg1/3Nb2/3)O3-PbTiO3 (PMN-PT) membrane. Phase-field simulations are performed to study the magnetic domain configurations and switching in CFO bilayers under piezostrains. An emerging interlayer parallel-to-antiparallel magnetic transition of the twisted CFO bilayer induced by appropriate piezostrain pulses generated from the PMN-PT membrane is discovered. Such a strain-induced parallel-to-antiparallel magnetic transition is non-volatile and reversible, arising from the synergistic interaction among spin, strain, and twisting order parameters. The present work provides a paradigm for designing novel spinotropic devices by taking advantage of the emerging phenomena generated by twisting.