Near Fermi level Electronic Structure of Pr$_{1-x}$Sr$_x$MnO$_3$: Photoemission Study

TL;DR

This study investigates the electronic structure of Pr$_{1-x}$Sr$_x$MnO$_3$ using photoemission, revealing a pseudogap linked to the insulator-metal transition and suggesting a common origin with charge-ordering gaps, along with potential half-metallicity.

Contribution

It provides experimental evidence of a pseudogap associated with the insulator-metal transition and proposes a possible half-metallic state in Pr$_{0.75}$Sr$_{0.25}$MnO$_3$ based on band structure calculations.

Findings

Abrupt shifts in near Fermi level density of states at Curie transition.

Pseudogap may share origin with charge-ordering gap.

Possible existence of half-metallicity in Pr$_{0.75}$Sr$_{0.25}$MnO$_3$.

Abstract

In this study, we report the observation of a pseudogap associated with the insulator-metal transition in compositions of Pr$_{1-x}$Sr$_x$MnO$_3$ system with no charge ordering. Our valence band photoemission study shows that the observed shifts in the near Fermi level density of states are abrupt at the Curie transtion and occur over an energy scale of $\sim$ 1 eV, strongly suggesting that the charge-ordering gap observed earlier in other manganites and the pseudogap observed here may indeed have same origin. These results could be understood within the framework of models based on electronic phase separation where it has been shown that the pseudogap is a generic feature of the mixed-phase compositions. Also, our band structure calculations on Pr$_{0.75}$Sr$_{0.25}$MnO$_3$ show the possible existence of half-metallicity in this system.