Ce-doping and reduction annealing effects on electronic states in Pr${}_{2-x}$Ce${}_x$CuO${}_4$ studied by Cu $K$-edge X-ray absorption spectroscopy

Abstract

We investigated Ce-substitution and reduction annealing effects on the electronic states at copper sites by Cu $K$-edge x-ray absorption near-edge structure measurements in Pr${}_{2-x}$Ce${}_x$CuO${}_{4+\alpha -\delta }$ (PCCO) with varying $x$ and $\delta$ (the amount of oxygen loss during annealing) values. Absorption near-edge spectra were modified by Ce-substitution and reduction annealing in a similar manner with increasing $x$ and $\delta$. Considering electron doping by Ce-substitution, this similarity indicates an increase of electron number at the copper sites due to annealing $n_{\mathrm{AN}}$. Thus, the total number of electrons is determined by the amount of Ce and oxygen ions. Furthermore, quantitative analyses of the spectra clarified that the number of Cu${}^{+}$ sites, corresponding to the induced electron number by Ce-substitution $n_{\mathrm{Ce}}$ increases linearly with $x$ in the as-sintered PCCO ($\delta =0$), whereas $n_{\mathrm{AN}}$ is not exactly equal to twice of $\delta$, which is expected from charge neutrality. For each $x$-fixed sample, $n_{\mathrm{AN}}$ tends to exceed 2$\delta$ with increasing $\delta$, suggesting the emergence of two types of carrier due to annealing.

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Cited by in corpus (8)

• Superconductivity induced by structural reorganization in the electron-doped cuprate Nd${}_{2-x}$Ce${}_x$CuO${}_4$
• Oxide Fermi liquid universality revealed by electron spectroscopy
• Oxidation annealing effects on the spin-glass-like magnetism and appearance of superconductivity in T*-type La${}_{1-x/2}$Eu${}_{1-x/2}$Sr${}_x$CuO${}_4$ (0.14 $\le x\le$ 0.28)
• Post-growth annealing effects on charge and spin excitations in Nd${}_{2-x}$Ce${}_x$CuO${}_4$
• Revisiting the phase diagram of T*-type La${}_{1-x/2}$Eu${}_{1-x/2}$Sr${}_x$CuO${}_4$ using Oxygen $K$-edge X-ray absorption spectroscopy
• Magnetism behavior of $T^{\prime }$-type Eu${}_2$CuO${}_4$ revealed by muon spin rotation/relaxation measurements
• Distinct variation of electronic states due to annealing in La${}_{1.8}$Eu${}_{0.2}$CuO${}_4$ and Nd${}_2$CuO${}_4$
• Electronic State of T'-Pr${}_{1.3-x}$La${}_{0.7}$Ce${}_x$CuO${}_4$ ($x=0.10$) Studied by Compton Scattering