On coherent states and the Self-Consistent Harmonic Approximation

• Autor(a) principal: Moura, A. R.
• Data de Publicação: 2019
• Outros Autores: Lopes, R. J. C.
• Tipo de documento: Artigo
• Idioma: eng
• Título da fonte: LOCUS Repositório Institucional da UFV
• Texto Completo: https://doi.org/10.1016/j.jmmm.2018.09.122; http://www.locus.ufv.br/handle/123456789/23656
• topic: Ferromagnetism; Coherent states; Self-Consistent Harmonic Approximation; Precession magnetization

We used the Self-Consistent Harmonic Approximation (SCHA) to study the thermodynamics of the precession magnetization in a two-dimensional isotropic ferromagnet. The SCHA treats the Hamiltonian in terms of the canonically conjugate operators Sz and φ (the azimuth angle) including renormalized temperature dependent parameters to take into account higher order interactions. It is well-known that in right conditions, a dynamic magnetic field is able to provide spin pumping and drives the system to a magnon Bose-Einstein condensation. The magnon condensate is a coherent state that presents minimal uncertainty for the Sz and φ operators. Consequently, 〈Sz〉 and 〈φ〉 should constitute natural fields to describe the model, which justifies the SCHA formalism. The results obtained are consistent with other theoretical and experimental works.