Pressure-induced melting of the orbital polaron lattice in La1-xSrxMnO3

TL;DR

This study investigates how pressure influences the orbital polaron lattice in lightly doped La1-xSrxMnO3, revealing that hopping and ferromagnetic interactions stabilize the lattice, with experimental evidence supporting these mechanisms.

Contribution

It provides new insights into the pressure dependence of the orbital polaron lattice and highlights the role of hopping and double exchange in its stabilization.

Findings

Hopping t significantly stabilizes the orbital polaron lattice.

Orbital polarons are ferromagnetic objects stabilized by local double exchange.

Experimental data support the Grueneisen scaling and orbital correlation analysis.

Abstract

We report on the pressure effects on the orbital polaron lattice in the lightly doped manganites $\mathrm{La_{1-x}Sr_xMnO_{3}}$, with $x\sim 1/8$. The dependence of the orbital polaron lattice on $negative$ chemical pressure is studied by substituting Pr for La in $\mathrm{(La_{1-y}Pr_y)_{7/8}Sr_{1/8}MnO_{3}}$. In addition, we have studied its hydrostatic pressure dependence in $\mathrm{(La_{0.9}Pr_{0.1})_{7/8}Sr_{1/8}MnO_{3}}$. Our results strongly indicate that the hopping $t$ significantly contributes to the stabilization of the orbital polaron lattice and that the orbital polarons are ferromagnetic objects which get stabilized by local double exchange processes. The analysis of short range orbital correlations and the verification of the Grueneisen scaling by hard x-ray, specific heat and thermal expansion data reinforces our conclusions.