Onset and melting of local orbital order

TL;DR

This paper investigates the temperature-dependent onset and melting of local orbital order in a two-orbital electron model, revealing how doping influences orbital correlations and their experimental signatures.

Contribution

It provides a detailed theoretical analysis of orbital order phenomena, including stabilization conditions and thermal behavior, aligning with neutron scattering observations.

Findings

Orbital order stabilizes above a critical doping level.

CE-type orbital correlations sharply onset near Curie temperature.

Orbital correlations are more stable in zig-zag AF state around x=0.5.

Abstract

The onset and melting of locally staggered charge/orbital correlations is investigated within a two-orbital correlated electron model with inter-orbital and inter-site Coulomb interactions. Beyond the critical doping concentration x_c ~ 0.2, the (pi,pi,pi) staggered orbital order in the ferromagnet is found to be stabilized at finite temperature. The CE-type orbital correlation exhibits a sharp onset close to the Curie temperature and rapid thermal melting, which provides quantitative understanding of the (pi/2,pi/2,0) feature observed near T_c in neutron scattering experiments. In the zig-zag AF state, the CE-type orbital correlations are found to be even more readily stabilized, but only within a narrow doping regime around x=0.5.