A high-resolution neutron study of at 77 K including magnetic properties

Abstract

The crystallographic and magnetic structures of at 77 K have been refined by Rietveld analysis of the high-resolution neutron powder diffraction data. The analysis indicates that has -type structure (). The Cr atoms occupy 12j, 6g and 4f sites with occupancies 0.12, 0.10 and 0.50 respectively, but Cr atoms are absent at 12k sites. The magnetic moments of all of the magnetic atoms lie in the plane perpendicular to the sixfold axes and exhibit planar magnetic anisotropy. The relations between the interesting abnormal magnetic properties and the structure are discussed.