Interplay between Strain-Stabilized Ferromagnetism and Charge Transport in Epitaxial LaCoO3-δ Thin Films
Abstract
The presence of ferromagnetic (FM) order in epitaxial LaCoO3 (LCO) thin films, in stark contrast to bulk, has gathered substantial recent attention. Due to the insulating nature of this strain-stabilized FM, however, little attention has been paid to electronic transport. Here, we present a systematic study of epitaxial LCO films (8-22 nm thick) grown under both tensile (on SrTiO3 and LSAT) and compressive strain (on LaAlO3 and SrLaAlO4), emphasizing not only magnetism but also transport. Tensile films exhibit ferromagnetism with saturation magnetization 1-1.5 μB/Co and Curie temperature 80 K, consistent with prior work. Polarized neutron reflectometry has also been performed, revealing a uniform magnetization depth profile with thickness. Most notably, transport, which is semiconducting in all cases, reveals an unanticipated correlation between strain-state and majority carrier type, supported by density functional theory calculations suggesting significant changes in conduction band structure under strain. This provides important clues to the origin of FM in this material.
Work supported by DOE Center for Quantum Materials under DOE-SC0016371.- Publication:
-
APS March Meeting Abstracts
- Pub Date:
- 2019
- Bibcode:
- 2019APS..MARB40006C