van der Waals CrSBr Alloys with Tunable Magnetic and Optical Properties

van der Waals magnets are attracting a great deal of attention for their potential integration into spintronic and magnonic technologies. CrSBr is an A-type antiferromagnet that shows a coupling between its electronic band structure and magnetic properties. This property is appealing for applications, and it also offers the possibility to investigate magnetic ground states and gigahertz magnons using visible optics techniques. Using Raman scattering and (magneto)-optical experiments, we describe the magnetic and optical properties of alloys of CrSBr_1-xCl_x with x ⩽ 0.46. Similar to CrSBr, these alloys are direct band gap semiconductors with a coupling of their electronic and magnetic properties. Exciton energies evolve weakly with composition, and we describe the large changes in the saturation magnetic fields and their implications for the magnetic properties. We show that both the interlayer magnetic exchange and electronic interactions are modified by halogen mixing, offering the possibility to tune magnon energies with alloy composition.