Temperature dependence of the chemical potential in La2-xSr xCuO4

Abstract

We have performed x-ray photoemission spectroscopy (XPS) measurements on the high-Tc superconductor La2-xSrxCuO 4 (LSCO) at various temperatures. From the shifts of core-level spectra, we have deduced the temperature dependence of the chemical potential in this system. In the underdoped region, the chemical potential shifts upwards with increasing temperature, whereas it shows an opposite shift in the overdoped region. These results qualitatively agree with the predictions of the t-J and tight-binding model calculations as well as thermodynamic quantities but a large quantitative discrepancy exists. © 2008 IOP Publishing Ltd.