Evidence of ferromagnetic quantum phase transition in Ba$_{1-x}$Sr$_x$VS$_3$

TL;DR

This study provides evidence of a ferromagnetic quantum phase transition in Ba$_{1-x}$Sr$_x$VS$_3$ driven by chemical pressure, showing an abrupt magnetic change at a critical composition and coexistence of phases at higher doping levels.

Contribution

It demonstrates the occurrence of a ferromagnetic quantum phase transition in Ba$_{1-x}$Sr$_x$VS$_3$ induced by chemical pressure, with detailed measurements across different compositions.

Findings

Abrupt onset of ferromagnetic order at x=0.07

Collapse of the unit cell at the transition

Coexistence of ferromagnetic and metallic phases at higher x

Abstract

Resistivity under pressure and magnetization measurements on Ba$_{1-x}$Sr$_x$VS$_3$ single crystals with 0 $\leq x \leq$ 0.18 and no sulphur deficiency show an abrupt onset of ferromagnetic (FM) order at a critical value $x$=0.07, concomitant to a change of the magnetic properties at the metal-insulator transition (MIT) and to a collapse of the unit cell at ambient temperature. A reduction of the MIT temperature to 50 K upon $x$ that scales as the V-S distance is also observed. This gives evidence of a chemical pressure induced quantum phase transition that stabilizes the incipient FM order of BaVS$_3$. The $0.07<x$ results suggest a coexistence of FM and metallic phases at larger $x$.