2004/11/29 by Hideaki Iwasawa, H. Iwasawa, T. Saitoh +9
Materials Science · Physics and Astronomy · #Advanced Condensed Matter Physics #Magnetic and transport properties of perovskites and related materials #Multiferroics and related materials #cond-mat.str-el
paper · pdf · doi:10.1103/physrevb.71.075106
7 pages text, 5 figures, to be pulished in Phys. Rev. B
arxiv created 2004/11/29 · openalex publication_date 2005/02/08 · arxiv updated 2009/12/01 · openalex created_date 2016/06/24 · openalex updated_date 2026/07/28
We have investigated the electronic structure of polycrystalline Ca2FeReO6 using photoemission spectroscopy and band-structure calculations within the local-density approximation+U (LDA+U) scheme. In valence-band photoemission spectra, a double-peak structure which is characteristic of the metallic double-perovskite series has been observed near the Fermi level (EF), although it is less distinct compared to the Sr2FeMoO6 case. The leading near-EF structure has a very weak spectral weight at EF above the metal-insulator transition (MIT) temperature TMI of \ensuremath∼140\phantom\rule0.3em0exK, and it loses the EF weight below TMI, forming a small energy gap. To reproduce this small energy gap in the calculation, we require a very large effective U (Ueff) for Re (4\phantom\rule0.3em0exeV) in addition to a relatively large Ueff for Fe (4\phantom\rule0.3em0exeV). Although the most of the experimental features can be interpreted with the help of the band theory, the overall agreement between the theory and experiment was not satisfactory. We demonstrate that the effective transfer integral between Fe and Re is actually smaller than that between Fe and Mo in Ca2FeMoO6, which can explain both the MIT and very high ferrimagnetic transition temperature.