Emergent Magnetic Phenomenon with Unconventional Structure in Epitaxial Manganate Thin Films

TL;DR

This study reveals complex magnetic phases in epitaxial LaMnO3 thin films, showing coexistence of ferromagnetic and antiferromagnetic orderings influenced by film thickness and interface structure, advancing interface engineering in oxides.

Contribution

It uncovers the coexistence of multiple magnetic phases in LaMnO3 thin films and links structural transitions to magnetic behavior, providing new insights into interface-controlled functionalities.

Findings

Ferromagnetism in 2 and 5-unit-cell films.

Ferromagnetic coupling in 8 and 10-unit-cell films.

Ferromagnetic/antiferromagnetic pinning in 15 and 20-unit-cell films.

Abstract

A variety of emergent phenomena has been enabled by interface engineering in the complex oxides heterostructures. While extensive attention has been attracted to LaMnO3 (LMO) thin films for observing the control of functionalities at its interface with substrate, the nature of the magnetic phases in the thin film is, however,controversial. Here, it is reported that the ferromagnetism in 2 and 5 unit cells thick LMO films epitaxially deposited (001)-SrTiO3 substrates ferromagnetic/ferromagnetic coupling in 8 and 10-unit-cell ones, and a striking ferromagnetic/antiferromagnetic pinning effect with apparent positive exchange bias in 15 and 20-unit-cell ones are observed. This novel phenomenon in both 15 and 20-unit-cell films indicates a coexistence of three magnetic orderings in a single LMO film.The high-resolution scanning transmission electron microscopy suggests a P21/n to Pbnm symmetry transition from interface to surface, with the spatial stratification of MnO6 octahedral morphology, corresponding to different magnetic orderings. These results should shed some new lights on manipulating the functionality of oxides by interface engineering.