Screening and Design of Bipolar Magnetic-Semiconducting Monolayers and Heterostructures

Bipolar magnetic semiconductors (BMSs) show great promise in spintronic devices because of their spin-dependent transport properties. Two-dimensional (2D) BMSs with electrically controllable spin polarization are ideal materials for bipolar manipulating the spin orientations at the nanoscale. Here, we systematically screened 2D BMSs from the 2DMatPedia database and found 11 promising candidates from 6531 structures. We attribute the formation of BMS electronic structure to the strong crystal field effect and low spin-exchange splitting in these structures. Moreover, we proposed an alternative way to construct BMS via engineering of heterostructures. The unique electronic structures of BMS can be achieved by stacking two half semiconductors with interlayer antiferromagnetic coupling and type-II band alignment. This approach was verified in CrI₃/VI₃ and CrSCl/CrSBr bilayer systems. Our work not only provides potential candidates of BMSs but also gives insight into the formation mechanism of BMSs, which will stimulate the experimental synthesis and application of BMSs.