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

Hisao Kobayashi, University of Hyogo
Toshihiro Nagao, University of Hyogo
Masayoshi Itou, Japan Synchrotron Radiation Research Institute
Sakae Todo, University of Tokyo
Bernardo Barbiellini, Northeastern University
Peter E. Mijnarends, Delft University of Technology
Arun Bansil, Northeastern University
Nobuhiko Sakai, University of Hyogo

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Originally posted at http://arxiv.org/abs/0908.3685v1. Preprint of an article published in Physical Review B, v.80 no.10, 2009.

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.