Electronic Raman scattering in Magnetite, Spin vs. Charge gap

TL;DR

This study uses Raman scattering to investigate electronic background changes in magnetite across the Verwey transition, revealing a broad peak at 370 wavenumbers that may indicate a spin or charge gap.

Contribution

It provides new Raman scattering data on magnetite's electronic background redistribution and identifies a broad peak potentially related to spin or charge gaps.

Findings

Electronic background extends up to 900 wavenumbers.

Background redistribution occurs below the Verwey transition.

A broad peak at 370 wavenumbers suggests a possible spin or charge gap.

Abstract

We report Raman scattering data of single crystals of magnetite (Fe3O4) with Verwey transition temperatures (Tv) of 123 and 117K, respectively. Both single crystals reveal broad electronic background extending up to 900 wavenumbers (~110 meV). Redistribution of this background is observed when samples are cooled below Tv. In particular, spectra of the low temperature phase show diminished background below 300 wavenumbers followed by an enhancement of the electronic background between 300 and 400 wavenumbers. To enhance the effect of this background redistribution we divide the spectra just below the transition by the spectra just above the transition. A resultant broad peak-like feature is observed, centered at 370 wavenumbers (45 meV). The peak position of this feature does not scale with the transition temperature. We discuss two alternative assignments of this feature to a spin or charge gap in magnetite.