Synchrotron-radiation spectroscopy of electron- and hole-doped collossal magneto-resistance double perovskites: BxA2−xFeMoO6 (A=Ba,Sr;B=La,K)

Abstract

The electronic structures of BxA2−xFeMoO6 (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 A2FeMoO6 (A=Ba,Sr) provide evidence for the mixed-valent Fe2+–Fe3+ states. The substitution of La3+ and K+ ions for A2+ ions causes the increasing Fe3+ component and increasing Fe2+ component, respectively. The states close to the Fermi level have mainly the Mo–Fe t2g(↓) 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 t2g(↓) states.