Research & Reviews: Journal of Material Sciences
MenuISSN:2321-6212
ISSN:2321-6212
Leonardo S Lima
Centro Federal de Educa�§�£o Tecnologica de Minas Gerais, Brazil
Posters & Accepted Abstracts: Res. Rev. J Mat. Sci
The local spontaneous symmetry breaking is a general phenomenon in condensed matter physics. It is characterized by the fact that the action has a local symmetry but the quantum theory, instead of having a unique vacuum state which respects this symmetry, has a family of degenerate vacua that transform into each other under the action of the symmetry group. A simple example is given by a ferromagnetic model in which the act governing its microscopic dynamics is invariant under spatial rotations. A kind of local gauge invariance or spontaneous breaking of U(1) gauge symmetry is realized in nature in the phenomenon of superconductivity. We have proposed a Meissner mechanism for the spin transport in quantum spin systems that to have various applications in spintronics. Besides, we study about the behavior of the AC spin conductivity in the neighborhood of a quantum phase transition in a frustrated spin model such as the antiferromagnet in the compass lattice with single ion anisotropy at T=0. Our results show the curve of conductivity varying strongly with the behavior of the critical anisotropy Dc and J2. Katukuri et al. have shown that individual layers of Ba2IrO4 provided a good realization of the quantum compass model on the square lattice. Zhang et al. have used the Heisenberg model with compass interactions to study the compound Sr2IrO4 and pointed out that it has a close resemblance to the cuprate superconductors such as La2CuO4 and that many interesting phenomena common to the cuprates are also found in Sr2IrO4.