Spin-Phonon Coupling, Spin Waves, and Other Magnetic Phenomena in Layered XPS₃ Materials via Raman Spectroscopy

Raman spectroscopy is a powerful, non-destructive optical method to probe the fundamental physics of two-dimensional (2D) layered materials through inelastic scattering. An amazing amount of information is quantified from the spectra such as layer thickness, disorder, edge and grain boundaries, strain, etc. More interestingly for 2D materials is that Raman efficiently probes the evolution of the electron-phonon and spin-phonon interactions as a function of temperature, laser energy, polarization, and magnetic field. Using our unique magneto-Raman capabilities, we study the magnetic properties of the metal phosphorus trisulfide family (XPS₃, where X = Fe, Mn, and Ni) which are layered antiferromagnetic semiconductors. While the three materials have the same crystal structure, their varying spin structures result in distinct behavior as a function of temperature and magnetic field, which will be presented herein. In FePS₃, we investigate the splitting and shifting of a non Γ-point phonon mode below the Neel temperature that is not present in MnPS₃, as well as the emergence of a spin wave with anomalous symmetry behavior. In addition, we have studied the apparent two-magnon mode in NiPS₃ under various conditions.