In:
Chinese Physics B, IOP Publishing, Vol. 32, No. 8 ( 2023-08-01), p. 087504-
Abstract:
The origin of ferromagnetism in epitaxial strained LaCoO 3− x films has long been controversial. Here, we investigated the magnetic behavior of a series of oxygen vacancy-ordered LaCoO 3− x films on different substrates. Obvious ferromagnetism was observed in perovskite LaCoO 3 /LSAT (LSAT = (LaAlO 3 ) 0.3 (SrAlTaO 6 ) 0.7 ) and LaCoO 3 /SrTiO 3 films, while LaCoO 3 /LaAlO 3 films showed weak ferromagnetic behavior. Meanwhile, LaCoO 2.67 films exhibited antiferromagnetic behavior. An unexpected low-temperature ferromagnetic phenomenon with a Curie temperature of ∼ 83 K and a saturation magnetization of ∼ 1.2 μ B /Co was discovered in 15 nm thick LaCoO 2.5 /LSAT thin films, which is probably related to the change in the interface CoO 6 octahedron rotation pattern. Meanwhile, the observed ferromagnetism gradually disappeared as the thickness of the film increased, indicating a relaxation of tensile strain. Analysis suggests that the rotation and rhombohedral distortion of the CoO 6 octahedron weakened the crystal field splitting and promoted the generation of the ordered high-spin state of Co 2+ . Thus the super-exchange effect between Co 2+ (high spin state), Co 2+ (low spin state) and Co 2+ (high spin state) produced a low-temperature ferromagnetic behavior. However, compressive-strained LaCoO 2.5 film on a LaAlO 3 substrate showed normal anti-ferromagnetic behavior. These results demonstrate that both oxygen vacancies and tensile strain are correlated with the emergent magnetic properties in epitaxial LaCoO 3− x films and provide a new perspective to regulate the magnetic properties of transition oxide thin films.
Type of Medium:
Online Resource
ISSN:
1674-1056
DOI:
10.1088/1674-1056/acafdc
Language:
Unknown
Publisher:
IOP Publishing
Publication Date:
2023
detail.hit.zdb_id:
2412147-2
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