Investigation of structural changes in chiral magnet Cr1∕3NbS2 under application of pressure

Abstract

We perform structural analysis experiments on the chiral magnet Cr1∕3NbS2, in which Cr3+ ions are inserted between hexagonal NbS2 layers. The noncentrosymmetrical nature of the inserted Cr3+ appears as a distorted CrS6 octahedron. Under the application of hydrostatic pressure, the lattice shrinks significantly along the c-axis rather than the a-axis. However, at a pressure P of approximately 3–4 GPa, a kink in the rate of decrease in the lattice parameters is observed, and the slight movement of a Nb atom along the c-axis brings about a decrease in the distortion of the CrS6 octahedron. This structural change qualitatively suggests a decrease in the strength of the Dzyaloshinskii-Moriya (D-M) interaction. Under hydrostatic pressure, the magnetic ordering temperature TC decreases, and dTC/dP exhibits a slight change at around 3 GPa. A series of experiments indicates that the change in the structural symmetry of the CrS6 octahedron influences the exchange network between Cr3+ ions as well as the D-M interaction.