%0 Journal Article
%A Alshalawi, Dhoha
%A Alonso, Jose Maria
%A Landa-Canovas, Angel R.
%A Presa Muñoz De Toro, Patricia Marcela De La
%T Transition from AFM spin canting to spin glass-AFM exchange as particle size decreases in LaFeO_3
%D 2023
%U https://hdl.handle.net/20.500.14352/87342
%X 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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