Structural disorder versus chiral magnetism in Cr1/3NbS2
Abstract
The crystal structure of a disordered form of Cr1/3NbS2 has been characterized using diffraction and inelastic scattering of synchrotron radiation. In contrast to the previously reported symmetry (P6322), the crystal can be described by a regular twinning of an average P63 structure with three disordered positions of the Cr ions. Short-range correlations of the occupational disorder result in a quite intense and structured diffuse scattering; a static nature of the disorder was unambiguously attributed by the inelastic x-ray scattering. The diffuse scattering has been modeled using a reverse Monte-Carlo algorithm assuming a disorder of the Cr sub-lattice only. The observed correlated disorder of the Cr sub-lattice reduces the temperature of the magnetic ordering from 130 K to 88 K and drastically modifies the field dependence of the magnetization as it is evidenced by the SQUID magnetometery. We conclude, that in contrast to the helicoidal spin structure assumed for P6322 form, the compound under study is ferromagnetically ordered with a pronounced in-plane anisotropy.