Substitution effects on the temperature vs. magnetic-field phase diagrams of the quasi-1D effective Ising spin-1/2 chain system BaCo$_2$V$_2$O$_8$

TL;DR

This study explores how various chemical substitutions in BaCo$_2$V$_2$O$_8$ affect its temperature and magnetic-field phase diagrams, revealing the impact on magnetic ordering and anisotropy in this quasi-1D Ising spin-1/2 system.

Contribution

It provides a comprehensive analysis of substitution effects on the magnetic phase diagrams of BaCo$_2$V$_2$O$_8$, including full-range Sr substitution and partial transition metal or magnesium doping.

Findings

Substitutions modify the phase diagram topology and critical fields.

Magnetic and structural properties are sensitive to chemical doping.

Phase diagrams exhibit significant anisotropy depending on substitution type.

Abstract

BaCo$_2$V$_2$O$_8$ is a one-dimensional antiferromagnetic spin-1/2 chain system with pronounced Ising anisotropy of the magnetic exchange. Due to finite interchain interactions long-range antiferromagnetic order develops below $T_{\rm N} \simeq 5.5$ K, which is accompanied by a structural distortion in order to lift magnetic frustration effects. The corresponding temperature $vs. $ magnetic-field phase diagram is highly anisotropic with respect to the magnetic-field direction and various details are still under vivid discussion. Here, we report the influence of several substitutions on the magnetic properties and the phase diagrams of BaCo$_2$V$_2$O$_8$. We investigate the substitution series Ba$_{\text{1-x}}$Sr$_{\text{x}}$Co$_{\text{2}}$V$_{\text{2}}$O$_{\text{8}}$ over the full range $0\le x \le 1$ as well as the influence of a partial substitution of the magnetic Co$^{2+}$ by small amounts of other magnetic transition metals or by non-magnetic magnesium. In all cases, the phase diagrams were obtained on single crystals from magnetization data and/or high-resolution studies of the thermal expansion and magnetostriction.