The Effect of Disorder in an Orbitally Ordered Jahn-Teller Insulator

TL;DR

This study investigates how quenched disorder affects the orbital order and electronic phases in a two-dimensional Jahn-Teller insulator model, revealing disorder-induced suppression of order and emergence of metastable stripe structures.

Contribution

It introduces a Monte Carlo approach to analyze disorder effects on orbital order and uncovers disorder-driven phenomena in a Jahn-Teller insulator model.

Findings

Disorder suppresses long-range orbital order.

A thermally driven insulator-metal crossover occurs in intermediate coupling.

Metastable stripe-like orbitally disordered structures emerge with disorder.

Abstract

We study a two dimensional, two-band double-exchange model for $e_g$ electrons coupled to Jahn-Teller distortions in the presence of quenched disorder using a recently developed Monte-Carlo technique. In the absence of disorder the half-filled system at low temperatures is an orbitally ordered ferromagnetic insulator with a staggered pattern of Jahn-Teller distortions. We examine the finite temperature transition to the orbitally disordered phase and uncover a qualitative difference between the intermediate and strongly coupled systems, including a thermally driven insulator to metal crossover in the former case. Long range orbital order is suppressed in the presence of disorder and the system displays a tendency towards metastable states consisting of orbitally disordered stripe-like structures enclosing orbitally ordered domains.