Unusual coexistence of negative and positive charge transfer in mixed-valence NaxCa1-xCr2O4

Article

关键词: LEVEL PHOTOEMISSION SPECTRA;    ELECTRONIC-STRUCTURE;    COLOSSAL MAGNETORESISTANCE;    HOLES;    SPECTROSCOPY;    TRANSITION;    STATE;    OXIDE;   

DOI  :  10.1103/PhysRevB.96.245113

来源: SCIE

【 摘 要 】

We have investigated the electronic structure of NaxCa1-xCr2O4 using x-ray absorption spectroscopy together with Anderson impurity model calculations. We show NaxCa1-xCr2O4 takes an unusualmixed-valence electronic state in which the positive charge-transfer (CT) and the negative CT states coexist. While CaCr2O4 (one end member) exhibits a typical CT nature with strong covalent character, Na substitution causes a negative CT state with an oxygen hole. In NaCr2O4 (the other end member), positive CT and negative CT states coexist with equal weight. This unusual electronic state is in sharp contrast to the conventional mixed-valence description in which the ground state can be described by the mixture of Cr3+ (3d(3)) and Cr4+ (3d(2)).

【 授权许可】

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