Enhanced Pressure Dependence of Magnetic Exchange in A2+[V2]O4 Spinels Approaching the Itinerant Electron Limit

TL;DR

This study investigates how applying pressure affects magnetic transition temperatures in A2+[V2]O4 spinels, revealing a transition towards itinerant-electron behavior and identifying an intermediate phase with mobile polarons.

Contribution

It demonstrates a systematic enhancement of pressure dependence of TN as V-V separation approaches the itinerant-electron limit, and identifies an intermediate phase with mobile holes in Zn[V2]O4 and Mg[V2]O4.

Findings

Pressure increases TN dependence as V-V separation decreases.

Zn[V2]O4 and Mg[V2]O4 exhibit less localized electrons than previously believed.

An intermediate phase with mobile polarons is identified.

Abstract

We report a systematic enhancement of the pressure dependence of TN in A2+[V2]O4 spinels as the V-V separation approaches the critical separation for a transition to itinerant-electron behavior. An intermediate phase between localized and itinerant electron behavior is identified in Zn[V2]O4 and Mg[V2]O4 exhibiting mobile holes as large polarons. In Zn[V2]O4, cooperative ordering of V-V pairs below a Ts=TN does not totally suppress the V3+-ion spins at ambient pressure, but makes TN to decrease with pressure. Our results demonstrate that Zn[V2]O4 and Mg[V2]O4 are less localized than previously thought.