Emergent and robust ferromagnetic-insulating state in highly strained ferroelastic LaCoO3 thin films
Dong Li1, Hongguang Wang2, Kaifeng Li1
1College of Physics, MIIT Key Laboratory of Aerospace Information Materials and Physics, State Key Laboratory of Mechanics and Control for Aerospace Structures, Nanjing University of Aeronautics and Astronautics, 211106, Nanjing, China.
Nature Communications
|June 19, 2023
Summary
Tensile strain in LaCoO3 films induces ferromagnetism by creating ordered oxygen vacancies and altering cobalt ion states. This discovery offers insights into emergent ferromagnetic-insulating states for spintronic applications.
Area of Science:
- Materials Science
- Condensed Matter Physics
- Solid State Chemistry
Background:
- Transition metal oxides exhibit tunable properties for spintronics.
- Ferroelastic lanthanum cobalt oxide (LaCoO3) is typically paramagnetic in bulk.
- Unexpected ferromagnetism in strained LaCoO3 films lacks a clear mechanistic explanation.
Purpose of the Study:
- To elucidate the origin of ferromagnetism in tensile-strained LaCoO3 films.
- To investigate the roles of oxygen vacancies and structural changes.
- To understand the electronic state modifications leading to ferromagnetism.
Main Methods:
- Experimental characterization of strained LaCoO3 films.
- Analysis of oxygen vacancy ordering and CoO6 octahedral rotations.
- Density functional theory (DFT) calculations.
Main Results:
- Simultaneous observation of ordered oxygen vacancies and suppressed octahedral rotations.
- DFT calculations reveal modified Co 3d-O 2p hybridization.
- Weakened crystal-field splitting and facilitated high-spin state of Co ions.
Conclusions:
- Strain-induced structural and electronic changes drive ferromagnetism in LaCoO3 films.
- An emergent ferromagnetic-insulating state arises from ordered oxygen vacancies and high-spin Co ions.
- Findings suggest potential for low-power spintronic devices.
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