Gradual Disappearance of the Fermi Surface near the Metal-Insulator Transition in La$_{1-x}$Sr$_{x}$MnO$_{3}$

TL;DR

This study uses ARPES to observe how the Fermi surface in La$_{1-x}$Sr$_{x}$MnO$_{3}$ gradually disappears near the metal-insulator transition, highlighting spectral weight transfer due to electron-electron interactions.

Contribution

First ARPES observation of electronic structure changes across the MI transition in LSMO, revealing spectral weight transfer and pseudogap behavior.

Findings

Fermi surface gradually disappears near the MI transition

Spectral weight shifts from coherent band to Hubbard band

Presence of pseudogap in metallic phase

Abstract

We report the first observation of changes in the electronic structure of La$_{1-x}$Sr$_{x}$MnO$_{3}$ (LSMO) across the filling-control metal-insulator (MI) transition by means of in situ angle-resolved photoemission spectroscopy (ARPES) of epitaxial thin films. The Fermi surface gradually disappears near the MI transition by transferring the spectral weight from the coherent band near the Fermi level ($E_{F}$) to the lower Hubbard band, whereas a pseudogap behavior also exists in the ARPES spectra in the close vicinity of $E_{F}$ for the metallic LSMO. These results indicate that the spectral weight transfer derived from strong electron-electron interaction dominates the gap formation in LSMO associated with the filling-control MI transition.