Crystallographic Orientation Controls Contact and Spin-Photoresponse in 2D Magnetic Heterostructures

Abstract

Two-dimensional ferromagnetic semiconductors such as CrSBr offer exceptional air stability, strong magnetic anisotropy, and rich magneto-optoelectronic coupling, yet inefficient electrical contacts continue to limit carrier injection and spin transport in practical devices. Here, we show that crystallographic orientation in CrSBr/MnSBr heterojunctions provides atomic-scale control over contact type, the direction of the built-in electric field, interfacial charge transfer, and spin-dependent photocurrent. Using density functional theory and non-equilibrium Green function transport simulations, we compare lateral (x- and y-type) and vertical (z-type) interfaces. Lateral heterojunctions form low-barrier n-type or p-type Ohmic contacts through strong interfacial hybridization. In contrast, the vertical configuration yields a Schottky barrier due to weak van der Waals coupling. These orientation-dependent contacts translate directly into distinct quantum transport and rectification behaviors. Under illumination, the heterostructures exhibit strongly anisotropic, spin-polarized photocurrents with pronounced spectral selectivity: parallel magnetic configurations show a pronounced photoresponse in the infrared, while antiparallel configurations are selectively responsive in the ultraviolet. These results establish two fundamental design principles—interface dimensionality dictates Ohmic versus Schottky character and magnetic configuration controls infrared/ultraviolet spectral selectivity—unlocking a new degree of freedom for programmable spin-optoelectronic devices beyond conventional vertical heterostructures.