Direct observation of localization in the minority-spin-band electrons of magnetite below the Verwey temperature

TL;DR

This study provides direct experimental evidence that minority-spin electrons in magnetite become localized below the Verwey temperature, using reconstructed spin-uncompensated momentum density distributions from magnetic Compton profiles.

Contribution

It is the first to directly observe localization of minority-spin electrons in magnetite below the Verwey transition via momentum density measurements.

Findings

Minority-spin electrons are localized below the Verwey temperature.

Reconstructed momentum density changes from negative to positive across the transition.

Mechanical de-twinning enabled accurate measurements in a twinned crystal.

Abstract

Two-dimensional spin-uncompensated momentum density distributions, $\rho_{\rm s}^{2D}({\bf p})$s, were reconstructed in magnetite at 12K and 300K from several measured directional magnetic Compton profiles. Mechanical de-twinning was used to overcome severe twinning in the single crystal sample below the Verwey transition. The reconstructed $\rho_{\rm s}^{2D}({\bf p})$ in the first Brillouin zone changes from being negative at 300 K to positive at 12 K. This result provides the first clear evidence that electrons with low momenta in the minority spin bands in magnetite are localized below the Verwey transition temperature.