Highly anisotropic resistivities in the double-exchange model for strained manganites

TL;DR

This paper investigates the origin of highly anisotropic resistivities in strained manganites using a double-exchange model, revealing that orbital imbalance and nanoscale phase separation contribute to the observed anisotropy.

Contribution

It introduces a theoretical model showing that strain-induced orbital imbalance and nanoscale clustering cause resistivity anisotropy without needing phase separation.

Findings

Anisotropic resistivities are linked to orbital population imbalance caused by strain.

Nanoscale phase-separated clusters amplify resistivity anisotropy.

Superexchange interactions are not significant in explaining anisotropic resistivities.

Abstract

The highly anisotropic resistivities in strained manganites are theoretically studied using the two-orbital double-exchange model. At the nanoscale, the anisotropic double-exchange and Jahn-Teller distortions are found to be responsible for the robust anisotropic resistivities observed here via Monte Carlo simulations. An unbalanced in the population of orbitals caused by strain is responsible for these effects. In contrast, the anisotropic superexchange is found to be irrelevant to explain our results. Our model study suggests that highly anisotropic resistivities could be present in a wide range of strained manganites, even without (sub)micrometer-scale phase separation. In addition, our calculations also confirm the formation of anisotropic clusters in phase-separated manganites, which magnifies the anisotropic resistivities.