Magnetic field modulated photoelectric devices in ferromagnetic semiconductor CrXh (X = S/Se, h = Cl/Br/I) van der Waals heterojunctions

The interactive control between electron charge and spin is essential to spintronics. Two-dimensional (2D) ferromagnetic semiconductors (FMSs) are a kind of unique candidate materials that could lead to flexible magnetoelectric and magneto-optic applications. In this Letter, we construct a series of van der Waals heterostructures by 2D magnetic CrXh (X = S/Se, h = Cl/Br/I) monolayers. Based on first-principles calculations, both monolayers and heterostructures have been demonstrated as intrinsic FMSs with large magnetic moments, suitable bandgaps, good carrier mobility, and high Curie temperatures. Taking advantage of the heterojunction effect, one can precisely control the charge transport behavior by forming three types of band alignments. Under an external alternating magnetic field, CrSeBr/CrSeCl and CrSBr/CrSI heterostructures can reversibly reconfigure between type-II and type-I band alignments upon switching of the spin direction. Combining the robust magnetic ordering and distinctive spin-polarized band alignment, our designed CrXh based magnetic heterostructures are ideal candidates for innovative magnetic-field-modulated photoelectric devices for realizing ultrarapid and reversible “write-read” processes.