The metal-insulator transition and its relation to magnetic structure in (LaMnO3)2n/(SrMnO3)n superlattices

TL;DR

This study investigates how the electronic and magnetic properties of (LaMnO3)2n/(SrMnO3)n superlattices change with layer thickness, revealing a transition from metallic to insulating behavior linked to magnetic structure modulation and interface disorder.

Contribution

It demonstrates the correlation between metal-insulator transition and magnetic structure modulation in superlattices, highlighting the role of interface disorder and magnetic frustration.

Findings

Superlattices are metallic for n<=2 and insulating for n>=3.

Ferromagnetism is uniform in metallic state and modulated in insulating state.

Disorder at interfaces localizes states and is linked to magnetic frustration.

Abstract

Superlattices of (LaMnO3)2n/(SrMnO3)n (n=1 to 5), composed of the insulators LaMnO3 and SrMnO3, undergo a metal-insulator transition as a function of n, being metallic for n<=2 and insulating for n>=3. Measurements of transport, magnetization and polarized neutron reflectivity reveal that the ferromagnetism is relatively uniform in the metallic state, and is strongly modulated in the insulating state, being high in LaMnO3 and suppressed in SrMnO3. The modulation is consistent with a Mott transition driven by the proximity between the (LaMnO3)/(SrMnO3) interfaces. Disorder localizes states at the Fermi level at the interfaces for n>=3. We suggest that this disorder is due to magnetic frustration at the interfaces.