Controlling magnetism via electric fields addresses fundamental questions of magnetic phenomena and phase transitions1,2,3, and enables the development of electrically coupled spintronic devices, such as voltage-controlled magnetic memories with low operation energy4,5,6. Previous studies on dilute magnetic semiconductors such as (Ga,Mn)As and (In,Mn)Sb have demonstrated large modulations of the Curie temperatures and coercive fields by altering the magnetic anisotropy and exchange interaction2,4,7,8,9. Owing to their unique magnetic properties10,11,12,13,14, the recently reported two-dimensional magnets provide a new system for studying these features15,16,17,18,19. For instance, a bilayer of chromium triiodide (CrI3) behaves as a layered antiferromagnet with a magnetic field-driven metamagnetic transition15,16. Here, we demonstrate electrostatic gate control of magnetism in CrI3 bilayers, probed by magneto-optical Kerr effect (MOKE) microscopy. At fixed magnetic fields near the metamagnetic transition, we realize voltage-controlled switching between antiferromagnetic and ferromagnetic states. At zero magnetic field, we demonstrate a time-reversal pair of layered antiferromagnetic states that exhibit spin-layer locking, leading to a linear dependence of their MOKE signals on gate voltage with opposite slopes. Our results allow for the exploration of new magnetoelectric phenomena and van der Waals spintronics based on 2D materials.
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Work at the University of Washington was mainly supported by the Department of Energy, Basic Energy Sciences (DOE BES), Materials Sciences and Engineering Division (DE-SC0012509) and a University of Washington Innovation Award. Work at MIT was supported by the Center for Integrated Quantum Materials under National Science Foundation (NSF) grant DMR-1231319 as well as the Gordon and Betty Moore Foundation’s EPiQS Initiative through grant GBMF4541 to P.J.-H. D.R.K. was funded in part by a QuantEmX grant from ICAM and the Gordon and Betty Moore Foundation through grant GBMF5305 and from the NSF Graduate Research Fellowship Program (GRFP) under grant 1122374. Device fabrication has been partly supported by the Center for Excitonics, an Energy Frontier Research Center funded by the DOE BES under award DE-SC0001088. D.H.C.’s contribution was supported by DE-SC0002197. Work at CMU was also supported by DOE BES DE-SC0012509. W.Y. was supported by the Croucher Foundation (Croucher Innovation Award) and the HKU ORA. Work at ORNL (M.A.M.) was supported by the DOE BES Materials Sciences and Engineering Division. D.X. acknowledges the support of a Cottrell Scholar Award. X.X. acknowledges the support from the State of Washington funded Clean Energy Institute and from the Boeing Distinguished Professorship in Physics.
Supplementary Figures 1–5