Pressure-induced suppression of ferromagnetic phase in LaCoO3 nanoparticles |
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| Authors: | I. Fita D. Mogilyansky V. Markovich R. Puzniak A. Wisniewski L. Titelman L. Vradman M. Herskowitz V.N. Varyukhin G. Gorodetsky |
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| Affiliation: | 1. Institute of Physics, Polish Academy of Sciences, Aleja Lotnikow 32/46, 02-668 Warsaw, Poland;2. Donetsk Institute for Physics and Technology, National Academy of Sciences, R. Luxemburg str. 72, 83114 Donetsk, Ukraine;3. Department of Physics, Ben-Gurion University of the Negev, 84105 Beer-Sheva, Israel;4. Blechner Center for Industrial Catalysis and Process Development, Department of Chemical Engineering, Ben-Gurion University of the Negev, 84105 Beer-Sheva, Israel |
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| Abstract: | Magnetic and structural properties of nanocrystalline LaCoO3 with particle size ranging from 25 to 38 nm, prepared by the citrate method, were investigated. All nanoparticles exhibit ferromagnetism below TC ≈ 85 K. It was found that the unit-cell volume increases monotonically with decreasing particle size and ferromagnetic (FM) moment increases simultaneously with lattice expansion, whereas TC remains nearly unchanged. It appears that both magnetic and structural properties of LaCoO3 nanoparticles are size-dependent due to the surface effect. On the other hand, an applied pressure suppresses strongly the FM phase leading to its disappearance at ～11 kbar. Remarkably, the TC does not change visibly under pressure. Our data reveal that the ferromagnetism in LaCoO3 nanoparticles, likely related to the intermediate-spin (IS) Co3+ state, is simply controlled by the unit-cell volume. Within this scenario, the FM coupled IS states appear/disappear with expanding/compressing the lattice and/or Co–O bonds. |
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