Doping and Field-Induced Insulator-Metal Transitions in Half-Doped Manganites

TL;DR

This paper introduces a two-fluid model for half-doped manganites that explains their insulator-metal transitions driven by doping and magnetic fields, emphasizing the role of Jahn-Teller coupling and spin canting.

Contribution

It proposes a novel two-fluid framework to understand complex phase transitions in manganites, highlighting the interplay of spin, charge, and orbital effects at intermediate Jahn-Teller coupling.

Findings

Explains doping and field-induced insulator-metal transitions

Accounts for particle-hole asymmetry in transitions

Describes small transition fields in manganites

Abstract

We argue that many properties of the half-doped manganites may be understood in terms of a new two-(eg electron)-fluid description, which is energetically favorable at intermediate Jahn-Teller (JT) coupling. This emerges from a competition between canting of the core spins of Mn promoting mobile carriers and polaronic trapping of carriers by JT defects, in the presence of CE, orbital and charge order. We show that this explains several features of the doping and magnetic field induced insulator-metal transitions, as the particle-hole asymmetry and the smallness of the transition fields.