Crystal and Magnetic Structure of Polar Oxide HoCrWO${}_6$

Abstract

Polar magnetic oxide HoCrWO${}_6$ is synthesized and its crystal structure, magnetic structure, and thermodynamic properties are investigated. HoCrWO${}_6$ forms the polar crystal structure (space group Pna2${}_1$ (#33)) due to the cation ordering of W${}^{6+}$ and Cr${}^{3+}$. There is an antiferromagnetic transition at TN = 24.5 K along with the magnetic entropy change (~5 J.Kg.${}^{-1}$K${}^{-1}$ at 70 kOe). Neutron diffraction measurement indicates that both Cr and Ho sublattices are ordered with the moment of 2.32(5)${\mu }_B$ and 8.7(4)${\mu }_B$ at 2 K, respectively. While Cr forms A-type collinear antiferromagnetic (AFM) structure with magnetic moment along the $b$ axis, Ho sublattice orders in a non-coplanar AFM arrangement. A comparison with isostructural DyFeWO${}_6$ and DyCrWO${}_6$ indicates that the magnetic structure of this family of compounds is controlled by the presence or absence of eg electrons in the transition metal sublattice.

7 figures, 22 pages. Journal of magnetism and magnetic materials, 2020