Isotropic Kink and Quasiparticle Excitations in the Three-Dimensional Perovskite Manganite La$_{0.6}$Sr$_{0.4}$MnO$_3$

TL;DR

This study uses ARPES to reveal isotropic quasiparticle excitations and kinks in 3D manganite La$_{0.6}$Sr$_{0.4}$MnO$_3$, highlighting polaronic effects and contrasting with layered manganites.

Contribution

It provides the first direct ARPES evidence of isotropic quasiparticle behavior and electron-phonon coupling in a 3D perovskite manganite, contrasting with anisotropic excitations in layered counterparts.

Findings

Observation of quasiparticle peaks around the Fermi surface.

Detection of isotropic kinks in the band dispersion.

Polaronic quasiparticles driven by Jahn-Teller phonons are significant.

Abstract

In order to reveal many-body interactions in the three-dimensional (3D) perovskite manganite, we have performed an $in$ $situ$ angle-resolved photoemission spectroscopy (ARPES) on La$_{0.6}$Sr$_{0.4}$MnO$_3$ (LSMO) and investigated the behaviors of quasiparticles. We observe quasiparticle peaks around the Fermi momentum, both in the electron and the hole bands, and clear kinks throughout the hole Fermi surface in the ARPES band dispersion. The isotropic behavior sharply contrasts to the strong anisotropic quasiparticle excitation observed in layered manganites. These results suggest that polaronic quasiparticles by coupling of the electrons with Jahn-Teller phonons play an important role in the physical properties of the ferromagnetic metallic phase in 3D manganite LSMO.