Unveiling Magnetic Ground States in CsMCl₃ (M = Cu, Co, Mn) via Powder Neutron Diffraction

Triangular-lattice antiferromagnets (TLAs) provide a fertile ground for investigating geometrical frustration, quantum fluctuations, and exotic magnetic phases such as chiral and non-collinear spin textures. The CsMCl₃ (M = Cu, Co, Mn) family offers a versatile platform for such studies, combining low-dimensional magnetic interactions with diverse spin quantum numbers and anisotropies within a common crystallographic framework. While these compounds exhibit clear signatures of magnetic ordering, the precise nature of their magnetic ground states remains unresolved. In this proposal, we aim to determine the magnetic structures of CsCuCl₃, CsCoCl₃, and CsMnCl₃ through high-resolution powder neutron diffraction using the WISH instrument at the ISIS Neutron and Muon Facility. These materials are particularly compelling due to evidence of multi-step transitions, anisotropic spin dynamics, and potential coupling between crystallographic chirality and magnetic order. WISH’s high sensitivity and broad d-spacing range make it ideally suited to detect weak magnetic Bragg peaks and distinguish subtle differences between competing magnetic models. By performing temperature-dependent measurements across relevant phase transitions, this study will provide critical insights into the microscopic origin of magnetism in frustrated and low-dimensional systems, while establishing the role of spin magnitude and lattice symmetry in stabilizing complex magnetic phases.