We have performed Raman scattering measurements on bismuth ferrite (BiFeO3) nanoparticles and studied both magnetic and lattice modes. We reveal strong anomalies between 140 K and 200 K at the frequency of magnon and E(LO1), E(TO1), and A1(LO1) phonon modes. These anomalies are related to a surface expansion and are enhanced for nanoparticle sizes approaching the spin cycloidal length. These observations point out the strong interplay between the surface, the lattice, and the magnetism for sizes of BiFeO3 nanoparticles close to cycloid periodicity.
Impact of the surface phase transition on magnon and phonon excitations in BiFeO3 nanoparticles
Ian Aupiais, Pierre Hemme, Marc Allen, Alexis M. Scida, Xiao Lu, Christian Ricolleau, Yann Gallais, Alain Sacuto, Stanislaus S. Wong, Rogério de Sousa, Maximilien Cazayous; Impact of the surface phase transition on magnon and phonon excitations in BiFeO3 nanoparticles. Appl. Phys. Lett. 27 April 2020; 116 (17): 172903. https://doi.org/10.1063/5.0003853
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