Cooperative Jahn-Teller Effect on the Magnetic Structure of Manganese Oxides

TL;DR

This study explores how cooperative Jahn-Teller phonons influence the magnetic and orbital structures of LaMnO₃, showing they can stabilize certain magnetic phases without requiring strong Coulomb interactions.

Contribution

It demonstrates that cooperative Jahn-Teller effects alone can account for the magnetic structure of LaMnO₃, reducing the need for strong Coulomb interactions in theoretical models.

Findings

Jahn-Teller phonons stabilize A-type antiferromagnetic order.

C-type orbital structures are also stabilized by cooperative effects.

Results are robust even with explicit Coulomb interactions.

Abstract

The magnetic structure of LaMnO$_3$ is investigated on three-dimensional clusters of MnO$_6$ octahedra by using a combination of relaxation and Monte Carlo techniques. It is found that the cooperative Jahn-Teller phonons lead to the stabilization of A-type antiferromagnetic and C-type orbital structures in the physically relevant region of parameter space for LaMnO$_3$ with small corrections due to tilting effects. The results suggest that strong Coulomb interactions are not necessary for a qualitative description of undoped manganites. In fact, it is shown that the present result is not essentially changed even if the Coulomb interaction is explicitly included.