Verwey transition in Fe$_{3}$O$_{4}$ at high pressure: quantum critical behavior at the onset of metallization

TL;DR

This study identifies a quantum critical point at the metallization of Fe₃O₄ under high pressure, revealing critical behavior in resistivity and Verwey transition scaling, and comparing it with similar phenomena in Mott systems.

Contribution

It provides experimental evidence for a quantum critical point in Fe₃O₄ at high pressure and characterizes its critical behavior, which was not previously established.

Findings

Quantum critical point at ~8 GPa in Fe₃O₄

Verwey temperature scales as (1 - p/p_c)^{1/3}

Resistivity shows critical temperature dependence with n changing from 3 to 2.5

Abstract

We provide evidence for the existence of a {\em quantum critical point} at the metallization of magnetite Fe$_{3}$O$_{4}$ at an applied pressure of $p_{c} \approx 8$ GPa. We show that the present ac magnetic susceptibility data support earlier resistivity data. The Verwey temperature scales with pressure $T_{V}\sim (1-p/p_{c})^{\nu}$, with $\nu\sim 1/3$. The resistivity data shows a temperature dependence $\rho(T)=\rho_{0}+AT^{n}$, with $n\simeq 3$ above and 2.5 at the critical pressure, respectively. This difference in $n$ with pressure is a sign of critical behavior at $p_{c}$. The magnetic susceptibility is smooth near the critical pressure, both at the Verwey transition and near the ferroelectric anomaly. A comparison with the critical behavior observed in the Mott-Hubbard and related systems is made.