Transition from AFM spin canting to spin glass-AFM exchange as particle size decreases in LaFeO_3
In this work, we have studied structural and magnetic properties of LaFeO_3 as a function of the particle size d, from bulk (d >> 1 µm) to nanoscale (d ≈ 30 nm). A large number of twins were observed for large particles that disappear for small particle sizes. This could be related to the soft...
| Autores: | , , , |
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| Tipo de recurso: | artículo |
| Fecha de publicación: | 2023 |
| País: | España |
| Institución: | Universidad Complutense de Madrid (UCM) |
| Repositorio: | Docta Complutense |
| Idioma: | inglés |
| OAI Identifier: | oai:docta.ucm.es:20.500.14352/87342 |
| Acceso en línea: | https://hdl.handle.net/20.500.14352/87342 |
| Access Level: | acceso abierto |
| Palabra clave: | 538.9 Perovskite oxides Exchange bias Nanoparticles Nanostructure Física de materiales 2211 Física del Estado Sólido |
| Sumario: | In this work, we have studied structural and magnetic properties of LaFeO_3 as a function of the particle size d, from bulk (d >> 1 µm) to nanoscale (d ≈ 30 nm). A large number of twins were observed for large particles that disappear for small particle sizes. This could be related to the softening of the FeO_6 distortion as particle size decreases. It was observed that the bulk sample showed spin canting that disappeared for d ~ 125 nm and can be associated with the smoothening of the orthorhombic distortion. On the other hand, for d < 60 nm, the surface/volume ratio became high and, despite the high crystallinity of the nanoparticle, a notable exchange effect bias appeared, originated by two magnetic interactions: spin glass and antiferromagnetism. This exchange bias interaction was originated by the formation of a "magnetic core-shell": the broken bonds at the surface atoms give place to a spin glass behavior, whereas the inner atoms maintain the antiferromagnetic G-type order. The LaFeO_3 bulk material was synthesized by the ceramic method, whereas the LaFeO_3 nanoparticles were synthesized by the sol-gel method; the particle size was varied by annealing the samples at different temperatures. The physical properties of the materials have been investigated by XRD, HRTEM, TGA, and AC and DC magnetometry. |
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