Chemical potential shift in : Photoemission test of the phase separation scenario

¹ Department of Physics, University of Tokyo - Bunkyo-ku, Tokyo 113-0033, Japan
² Department of Complexity Science and Engineering, University of Tokyo Bunkyo-ku, Tokyo 113-0033, Japan
³ Department of Chemistry, Mie University - Tsu 514-8507, Japan
⁴ Institute of Chemical Research, Kyoto University - Uji, Kyoto 611-0011, Japan

Received: 12 February 2002
Accepted: 22 April 2002

Abstract

We have studied the chemical potential shift in LaSr_xMnO₃ as a function of doped hole concentration by core-level X-ray photoemission. The shift is monotonous, which means that there is no electronic phase separation on a macroscopic scale, whereas it is consistent with the nanometer scale cluster formation induced by chemical disorder. Comparison of the observed shift with the shift deduced from the electronic specific heat indicates that hole doping in LaSr_xMnO₃ is well described by the rigid-band picture. In particular no mass enhancement toward the metal-insulator boundary was implied by the chemical potential shift, consistent with the electronic specific-heat data.