Spin-order-dependent magneto-elastic interactions in two dimensional antiferromagnetic MnPSe₃ observed through Raman spectroscopy

Layered antiferromagnetic materials have emerged as a novel subset of the two dimensional family with promising physical properties which provide a highly accessible framework in which to examine a multitude of phenomena arising from a unique combination of low dimensionality, fast spin dynamics and a robustness to external magnetic fields. Specifically, transition metal phosphorous trichalcogenides, MPX3 (M = transition metal; X = chalcogen), hold a lot of promise for investigating fundamental interactions between magnetic and lattice degrees of freedom, and for the exploration of developing fields such as spintronics and magnonics. Here, we use a combination of temperature dependent Raman spectroscopy and density functional theory (DFT) to explore magnetic ordering-dependent interactions between the antiferromagnetic manganese spin degree of freedom and lattice vibrations via a Kramers-Anderson super-exchange pathway in both bulk and few layer manganese phosphorous triselenide (MnPSe3) from 5-250 K including the N´eel transition temperature of 74 K. We observe a non-linear temperature dependent shift of all seven Raman active phonon modes, including two magnetic modes (84 cm-1 and 109 cm-1), a hybridised two-magnon mode (126 cm-1) and four less studied phonon modes predominantly associated with the non-magnetic sub-lattice (143 cm-1, 156 cm-1, 173 cm-1, and 221 cm-1). These four Raman modes possess a non-trivial spin phonon coupling below the N´eel temperature. Using an analytical approach consisting of combining anharmonic temperature dependent shifts with magnetic-specific Brillouin function fitting to these four phonon lines, we extract a spin-phonon coupling constant for each mode.