Structural Disorder Induced Polaron Formation and Magnetic Scattering in the Disordered Holstein-Double Exchange Model

TL;DR

This study investigates how structural disorder caused by thermal effects influences polaron formation and magnetic scattering, leading to a metal-insulator transition in a disordered Holstein-Double Exchange model using Monte Carlo simulations.

Contribution

It provides a detailed microscopic understanding of the thermally driven metal-insulator transition in a disordered magnetic system, emphasizing the role of effective disorder and polaron formation.

Findings

Thermal evolution of lattice distortions shows increased disorder near transition.

Structural and hopping disorder distributions are characterized and linked to the MIT.

Proposes an 'Anderson-Holstein' transition phenomenology for the MIT.

Abstract

In this paper we present results on the disordered Holstein-Double Exchange model, explicitly in three dimension and `metallic' densities, obtained by using a recently developed Monte Carlo approach. Following up on our earlier paper, cond-mat/0406085, here we provide a detailed microscopic picture of the thermally driven metal-insulator transition (MIT) that arises close to the ferromagnet to paramagnet transition in this problem. This paper is focused mainly on the `diagnostics', clarifying the origin of the effective disorder that drives the MIT in this system. To that effect, we provide results on the thermal evolution of the distributions of (i) lattice distortions, (ii) the net `structural disorder' and (iii) the `hopping disorder' arising from spin randomness feeding back through the Hunds coupling. We suggest a phenomenology for the thermally driven MIT, viewing it as an `Anderson-Holstein' transition.