Pressure dependence of the Verwey transition in magnetite: an infrared spectroscopic point of view

TL;DR

This study uses infrared spectroscopy to explore how pressure influences the Verwey transition in magnetite, revealing changes in reflectance and phonon modes, and proposing a pressure-temperature phase diagram.

Contribution

It provides new insights into the pressure dependence of the Verwey transition through infrared spectroscopic measurements and phase diagram development.

Findings

Reflectance decreases drastically at the transition

Phonon modes split and activate at the transition

A pressure-temperature phase diagram is proposed

Abstract

We investigated the electronic and vibrational properties of magnetite at temperatures from 300 K down to 10 K and for pressures up to 10 GPa by far-infrared reflectivity measurements. The Verwey transition is manifested by a drastic decrease of the overall reflectance and the splitting of the phonon modes as well as the activation of additional phonon modes. In the whole studied pressure range the down-shift of the overall reflectance spectrum saturates and the maximum number of phonon modes is reached at a critical temperature, which sets a lower bound for the Verwey transition temperature T$_{\mathrm{v}}$. Based on these optical results a pressure-temperature phase diagram for magnetite is proposed.