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

TL;DR

This study uses in-situ photoemission to examine how epitaxial strain affects the electronic structure of Pr_{1-x}Ca_xMnO_3 thin films, revealing suppressed charge fluctuations and unique electronic behaviors compared to bulk samples.

Contribution

It provides new insights into the electronic structure of epitaxially strained PCMO thin films, highlighting the suppression of charge fluctuations and differences from bulk properties.

Findings

Chemical potential shifts monotonically with doping

No spectral weight transfer observed in valence band

Clear gap at Fermi level indicating electron localization

Abstract

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 of epitaxial strain on the electronic structure. We found that the chemical potential shifted monotonically with doping, unlike bulk PCMO, implying the disappearance of incommensurate charge fluctuations of bulk PCMO. In the valence-band spectra, we found a doping-induced energy shift toward the Fermi level (E_F) but there was no spectral weight transfer, which was observed in bulk PCMO. The gap at E_F was clearly seen in the experimental band dispersions determined by angle-resolved photoemission spectroscopy and could not be explained by the metallic band structure of the C-type antiferromagnetic state, probably due to localization of electrons along the ferromagnetic chain direction or due to another type of spin-orbital ordering.