Neutron-scattering-based evidence for interacting magnetic excitons in $\mathrm{LaCo}{\mathrm{O}}_3$

Journal Article · Sat Aug 01 00:00:00 EDT 2015 · Physical Review. B, Condensed Matter and Materials Physics

DOI:https://doi.org/10.1103/PhysRevB.92.060404· OSTI ID:1356990

El-Khatib, S.; Phelan, D.; Barker, J. G.; Zheng, H.; Mitchell, J. F.; Leighton, C.

Recent progress with the thermally-driven spin-state crossover in LaCoO3 has made it increasingly apparent that the nominally non-magnetic low spin ground state of this material actually hosts novel defect-'based magnetism. This is investigated here via a small-angle neutron scattering (SANS) study of LaCoO3-s crystals. The results provide: (i) the surprising finding that the spin-state crossover is clearly reflected in SANS via quasielastic/inelastic scattering from paramagnetic spin fluctuations/excitations, and (ii) evidence for the formation, likely around oxygen defects, of local entities known as magnetic excitons. The latter generate distinct magnetic scattering below 60 K, providing valuable quantitative information on exciton densities and interactions. Potential relevance to the unexpected ferromagnetism recently discovered in epitaxial LaCoO3 films is discussed.

• Research Organization: Argonne National Lab. (ANL), Argonne, IL (United States)
• Sponsoring Organization: USDOE Office of Science (SC), Basic Energy Sciences (BES)
• DOE Contract Number: AC02-06CH11357
• OSTI ID: 1356990
• Journal Information: Physical Review. B, Condensed Matter and Materials Physics, Vol. 92, Issue 6; ISSN 1098-0121
• Publisher: American Physical Society (APS)
• Country of Publication: United States
• Language: English