Explaining a Low-Temperature Magnetic Order in Annealed van der Waals Semiconductor CrSBr

Abstract

The van der Waals semiconductor CrSBr stands out as a promising 2D magnetic material due to its high ferromagnetic ordering temperature (135 K), near-infrared direct bandgap (1.5 eV), and stability in air. In this thesis we report on the detection of a low-temperature magnetic order in annealed CrSBr bulk single crystals using SQUID magnetometry. The order manifests as a broad bump centered at 75 K in magnetization measurements. We deduce that the order is the magnetic contribution of secondary phases, which we image and identify via SEM-EDS analysis. We determine that the secondary phase Cr₂S₃ is formed during annealing at 750°C or above and that the secondary phase CrBr₃ is also formed during annealing at 850°C.