  Layered magnetic transition-metal thiophosphate NiPS3 has unique
two-dimensional (2D) magnetic properties and electronic behavior. The
electronic band structure and corresponding magnetic state are expected to
sensitive to the interlayer interaction, which can be tuned by external
pressure. Here, we report an insulator-metal transition accompanied with
magnetism collapse during the 2D-3D crossover in structure induced by
hydrostatic pressure. A two-stage phase transition from monoclinic (C2=m) to
trigonal (P-31m) lattice is identified by ab initio simulation and confirmed by
high-pressure XRD and Raman data, corresponding to a layer by layer slip
mechanism along the a-axis. Temperature dependence resistance measurements and
room temperature infrared spectroscopy show that the insulator-metal transition
occurs near 20 GPa as well as magnetism collapse, which is further confirmed by
low temperature Raman measurement and theoretical calculation. These results
establish a strong correlation among the structural change, electric transport,
and magnetic phase transition and expand our understandings about the layered
magnetic materials.
