In-situ photoemission study of Pr_{1-x}Ca_xMnO_3 epitaxial thin films with suppressed charge fluctuations

摘要

We have performed an {\it in-situ} photoemission study of Pr_{1-x}Ca_xMnO_3(PCMO) thin films grown on LaAlO_3 (001) substrates and observed the effect ofepitaxial strain on the electronic structure. We found that the chemicalpotential shifted monotonically with doping, unlike bulk PCMO, implying thedisappearance of incommensurate charge fluctuations of bulk PCMO. In thevalence-band spectra, we found a doping-induced energy shift toward the Fermilevel (E_F) but there was no spectral weight transfer, which was observed inbulk PCMO. The gap at E_F was clearly seen in the experimental band dispersionsdetermined by angle-resolved photoemission spectroscopy and could not beexplained by the metallic band structure of the C-type antiferromagnetic state,probably due to localization of electrons along the ferromagnetic chaindirection or due to another type of spin-orbital ordering.