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Charge ordering and chemical potential shift in La$_{2-x}$Sr$_x$NiO$_4$ studied by photoemission spectroscopy

M. Satake·K. Kobayashi·T. Mizokawa·A. Fujimori·T. Tanabe·T. Katsufuji·Y. Tokura
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Abstract

We have studied the chemical potential shift in La$_{2-x}$Sr$_x$NiO$_4$ and the charge ordering transition in La$_{1.67}$Sr$_{0.33}$NiO$_4$ by photoemission spectroscopy. The result shows a large ($\sim$ 1 eV/hole) downward shift of the chemical potential with hole doping in the high-doping regime ($δ\gtrsim$ 0.33) while the shift is suppressed in the low-doping regime ($δ\lesssim$ 0.33). This suppression is attributed to a segregation of doped holes on a microscopic scale when the hole concentration is lower than $δ\simeq 1/3$. In the $δ= 1/3$ sample, the photoemission intensity at the chemical potential vanishes below the charge ordering transition temperature $T_{\rm CO}=$ 240 K.

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M. Satake, K. Kobayashi, T. Mizokawa, A. Fujimori, T. Tanabe, T. Katsufuji, Y. Tokura. 1999-08-02. Charge ordering and chemical potential shift in La$_{2-x}$Sr$_x$NiO$_4$ studied by photoemission spectroscopy. https://doi.org/10.1103/physrevb.61.15515

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