Análise de curvas espectrais do modelo de Ising transverso com interações de multispins

• Ano de defesa: 2022
• Autor(a) principal: Souza, Wescley Luiz de
• Tipo de documento: Tese
• Tipo de acesso: Acesso aberto
• Idioma: por
• Instituição de defesa: Universidade Federal de Mato Grosso; Brasil; Instituto de Física (IF); UFMT CUC - Cuiabá; Programa de Pós-Graduação em Física
• Palavras-chave em Português: Análise espectral; Método de relações de recorrência; Modelo de Ising; Interação multispin; Exchange narrowing; CNPQ::CIENCIAS EXATAS E DA TERRA::FISICA; Spectral analysis; Method of recurrence relations; Ising model; Multispin interactions
• Link de acesso: http://ri.ufmt.br/handle/1/6567

An open question in spintronics is the control of spin dynamics, since long relaxation times are required for the realization of information storage and processing devices. Multiferroic materials have been considered for applications with this purpose due to the perspective of controlling charges and spins by electromagnetic fields. In this context, spin quantum systems with multiple couplings have been shown a key tool in the description of dynamic properties. In particular, chains with cyclic 4-spins interactions are of great interest, since they have already been considered to explain, for example, extra magnetic orders in perovskite multiferroic materials and in the improvement of short distance quantum communication protocol. This corroborates the relevance of studying classes of spin models with multiple interactions. In this work, the dynamics of the transverse field spin-1/2 bsing ladder model with 4-spins plaquette interaction is investigated through the recurrence relations method (RRM). Differently from other approaches, the RRM allows to obtain dynamical properties in the limit of infinite system. For a constant transverse field the relaxation curves show a longer relaxation time with interaction increasing an the spectral lines shows a predominant lorentzian behavior in the central body and a gaussian shape in the tails. With a random field, a dynamic transition from the central peak to the collective mode regime is observed, and the spectral lines reveal a predominance of the lorentzian profile of multiple peaks in the central part and a gaussian fit in the tails. This combination of lorentzian and gaussian curves is tipically found in spectroscopic analyses of materials such as graphene, perovskites and models of interacting molecules. The exchange narrowing phenomenon which occurs in the constant-field spectral curves obtained is experimentally observed via electron spin resonance and provides information. concerning magnetic and structural properties in doped semiconductor compounds Therefore, the theoretical results from this work bring new perspectives for the understanding of spin dynamics in materials with a hight technological potential.