Field-induced exciton condensation in LaCoO3

TL;DR

This paper investigates how external magnetic fields induce exciton condensation in LaCoO3, highlighting the temperature-dependent critical fields and the role of high mobility of intermediate spin excitations in the transition.

Contribution

It demonstrates that exciton condensation in LaCoO3 can be driven by magnetic fields and explains the temperature dependence, supporting the exciton scenario over spin-state ordering.

Findings

Magnetic field induces exciton condensation in LaCoO3.

Temperature dependence of critical field supports exciton scenario.

High mobility of intermediate spin excitations facilitates condensation.

Abstract

Motivated by recent observation of magnetic field induced transition in LaCoO3 we study the effect of external field in systems close to instabilities towards spin-state ordering and exciton condensation. We show that, while in both cases the transition can be induced by an external field, temperature dependencies of the critical field have opposite slopes. Based on this result we argue that the experimental observations select the exciton condensation scenario. We show that such condensation is possible due to high mobility of the intermediate spin excitations. The estimated width of the corresponding dispersion is large enough to overrule the order of atomic multiplets and to make the intermediate spin excitation propagating with a specific wave vector the lowest excitation of the system.