Synchrotron-radiation spectroscopy of electron- and hole-doped collossal magneto-resistance double perovskites: B(x)A(2-x)FeMoO(6) (A=Ba,Sr; B=La,K)

Abstract

The electronic structures of B(x)A(2-x)FeMoO(6) (A=Ba,Sr;B=La,K) double perovskites have been investigated by using photoemission spectroscopy and soft-x-ray absorption spectroscopy (XAS) near the Fe 2p and O 1s absorption edges. The Fe 2p XAS spectra of undoped A(2)FeMoO(6) (A=Ba,Sr) provide evidence for the mixed-valent Fe2+-Fe3+ states. The substitution of La3+ and K+ ions for A(2+) ions causes the increasing Fe3+ component and increasing Fe2+ component, respectively. The states close to the Fermi level have mainly the Mo-Fe t(2g)(down arrow) character, consistent with the Fe2+-Fe3+ mixed-valent states. As the amount of the K+ substitution increases in KxSr2-xFeMoO6, the photoemission intensity near the Fermi level decreases, reflecting the decreasing carriers and the decreasing bandwidth of the itinerant t(2g)(down arrow) states. (C) 2006 American Institute of Physics.