Paramagnetic magnetostriction in the chiral magnet CrNb3 S6 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 Tc of 127 K. The present paramagnetic MS prominently appeared under H∥ the ab plane (easy plane) as opposed to under H∥ the c axis. Features observed in the paramagnetic MS effect significantly differ from those of the spontaneous MS in the vicinity of Tc [Phys. Rev. B 102, 014446 (2020)2469-995010.1103/PhysRevB.102.014446]. 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)2469-995010.1103/PhysRevB.99.174439]. 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 CrS6 octahedron, resulting in the changes in Cr-Nb(4f) distance via the change in the hybridization between Cr-a1g and Nb-4dz2 orbitals.