Ce substitution and reduction annealing effects on electronic states in PrCeCuO studied by Cu -edge X-ray absorption spectroscopy

Asano, Shun*; Ishii, Kenji*; Matsumura, Daiju   ; Tsuji, Takuya  ; Ina, Toshiaki*; Suzuki, Kensuke*; Fujita, Masaki*

We investigated the Ce substitution and reduction annealing effects on the electronic states at copper sites by Cu -edge X-ray absorption near-edge structure measurements in PrCeCuO (PCCO) with varying and (amount of oxygen loss during annealing). Absorption near-edge spectra were modified by Ce substitution and reduction annealing similarly with increasing and . Considering electron doping by Ce substitution, this similarity indicates an increase in electron number at the copper sites due to annealing (). Furthermore, quantitative analyses of the spectra clarified that the number of Cu sites, corresponding to the induced electron number by Ce substitution increases linearly with in the as-sintered PCCO, whereas is not exactly equal to 2. For each -fixed sample, tends to exceed 2 with increasing , suggesting the emergence of two types of carrier due to annealing.