Infrared studies of magnetite under high pressure

Abstract

The pressure-induced changes in the optical response of magnetite were studied by infrared reflectivity measurements at room temperature. The pressure-induced redshift of the pronounced midinfrared absorption band confirms the polaronic transport mechanism. The low-frequency conductivity increases and the phonon modes harden with increasing pressure. We discuss our results in terms of the proposed pressure-induced charge transfer among the different Fe sites.

Keywords:

• magnetite
• infrared response
• polarons

Acknowledgements

We acknowledge the ANKA Angströmquelle Karlsruhe for the provision of beamtime and thank B. Gasharova, Y.-L. Mathis, D. Moss, and M. Süpfle for assistance at the beamline ANKA-IR. Financial support by the Bayerische Forschungsstiftung and the DFG through SFB 484 is gratefully acknowledged.