Paramagnetic magnetostriction in the chiral magnet CrNb3S6 at room temperature

We report that the magnetostriction (MS) effects occur in a paramagnetic state of a chiral magnet CrNb3S6. Through a series of experimental tests at room temperature, structural changes were observed at the level of a unit cell. The structural parameters are dependent of the strength and direction of magnetic field (H) even at temperature excessively higher than the magnetic ordering temperature T-c of 127 K. The present paramagnetic MS prominently appeared under H parallel to the ab plane (easy plane) as opposed to under H parallel to the c axis. Features observed in the paramagnetic MS effect significantly differ from those of the spontaneous MS in the vicinity of T-c [Phys. Rev. B 102, 014446 (2020)]. In this material, the orbital angular momentum L of Cr originates from the hybridization between Cr and Nb, and L is strongly coupled with the crystal structure [Phys. Rev. B 99, 174439 (2019)]. The present study clarified that the symmetry of the CrS6 octahedron is sensitive to H even at room temperature. The paramagnetic spin-orbit coupling should induce the distortion of CrS(6)( )octahedron, resulting in the changes in Cr-Nb(4f) distance via the change in the hybridization between Cr-a(1g) and Nb-4d(z)2 orbitals.