Interface Ferromagnetism in a SrMnO3/LaMnO3 Superlattice

TL;DR

This study uses resonant soft x-ray absorption to reveal interface ferromagnetism in a SrMnO3/LaMnO3 superlattice, showing magnetic phase development linked to doped hole modulation and valence states.

Contribution

It presents a new model explaining interface ferromagnetism through resonant scattering and temperature-dependent hopping, highlighting the role of doped holes and valence states.

Findings

Resonant scattering indicates ferromagnetic phase at interfaces.

Magnetic variation correlates with doped hole density modulation.

Model includes temperature-dependent hopping between Mn sites.

Abstract

Resonant soft x-ray absorption measurements at the O K edge on a SrMnO3/LaMnO3 superlattice show a shoulder at the energy of doped holes, which corresponds to the main peak of resonant scattering from the modulation in the doped hole density. Scattering line shape at the Mn L3,2 edges has a strong variation below the ferromagnetic transition temperature. This variation has a period equal to half the superlattice superperiod and follows the development of the ferromagnetic moment, pointing to a ferromagnetic phase developing at the interfaces. It occurs at the resonant energies for Mn3+ and Mn4+ valences. A model for these observations is presented, which includes a double-exchange two-site orbital and the variation with temperature of the hopping frequency tij between the two sites.