Crystal and Magnetic Structure of Polar Oxide HoCrWO$_6$

TL;DR

This study synthesizes and characterizes HoCrWO$_6$, revealing its polar crystal structure, antiferromagnetic transition at 24.5 K, and detailed magnetic ordering of Ho and Cr sublattices, contributing to understanding magnetic structures in polar oxides.

Contribution

First detailed investigation of HoCrWO$_6$'s crystal and magnetic structure, highlighting the role of eg electrons in magnetic ordering within this family of compounds.

Findings

HoCrWO$_6$ has a polar structure due to cation ordering.

Antiferromagnetic transition occurs at 24.5 K.

Cr and Ho sublattices exhibit distinct magnetic orderings.

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.