Abstract
Magnetism in lanthanum cobaltite (LCO, LaCoO3) appears to be strongly dependent on strain, defects, and nanostructuring. LCO on strontium titanate (STO, SrTiO3) is a ferromagnet with an interesting strain relaxation mechanism that yields a lattice modulation. However, the driving force of the ferromagnetism is still controversial. Experiments debate between a vacancy-driven or strain-driven mechanism for epitaxial LCO's ferromagnetism. We found that a weak lateral modulation of the superstructure is sufficient to promote ferromagnetism. Our research also showed that ferromagnetism appears under uniaxial compression and expansion. Although earlier experiments suggest that bulk LCO is nonmagnetic, our diffusion Monte Carlo calculations found that magnetic phases have a lower energy ground state for bulk LCO. This paper discusses recent experiments indicating a more complicated picture for the bulk magnetism and closer agreement with our calculations. The role of defects are also discussed through excited-state calculations.
| Original language | English |
|---|---|
| Article number | 124414 |
| Journal | Physical Review Materials |
| Volume | 3 |
| Issue number | 12 |
| DOIs | |
| State | Published - Dec 26 2019 |
Funding
We are grateful for helpful discussions with Dr. Jaime Fernandez-Baca and Dr. Feng Ye on analyzing our neutron-diffraction experiments. The work was supported by the Materials Sciences and Engineering Division of the Office of Basic Energy Sciences, US Department of Energy (DOE). Computational resources were provided by the Oak Ridge Leadership Computing Facility at the Oak Ridge National Laboratory, supported by the Office of Science of the DOE under Contract No. DE-AC05-00OR22725. APPENDIX: