Nonlinear phonon dynamics in the layered antiferromagnetic FePS3

The coherent excitation of lattice vibrations is a powerful method to manipulate the properties of quantum materials. Nonlinear phonon couplings can be used for directional control of transient structural distortions, also called nonlinear phononic rectification, where the direction of distortion can be controlled through the polarization of the incident light pulse. Here, we apply this principle to the two-dimensional layered antiferromagnet FePS3. We investigate the nonlinear lattice dynamics that follow the excitation with an ultrashort terahertz pulse and compare our results to topical experiments on phonon driving in this material. We use a combination of phenomenological models for the coherent phonon dynamics and first-principles calculations based on density functional theory for realistic input parameters to evaluate the possible nonlinear excitation pathways and structural distortions that can be induced. We in particular focus on excitations of the interlayer shear modes in FePS3 in order to determine whether control of the magnetic exchange interactions can be achieved through this mechanism.