Leonardo dos Santos Lima
Federal Center for Technological Education of Minas Gerais, Brazil
Title: Spin superfluidity in the frustrated two-dimensional anisotropic XY model
Biography
Biography: Leonardo dos Santos Lima
Abstract
The progress in the investigations of Spin Supercurrent and magnon BEC was recently described in the review [1]. Particularly there was overviewed the spin supercurrent Josephson Effect which is the response of the current to the phase between two weakly connected regions of coherent quantum states. For quasiparticles such as magnons and excitons in Bose-Einstein condensation (BEC), it demonstrates the interference between two quasiparticles condensates. Spin current as a function of the phase difference across the junction, α1−α2 , where α1 and α2 are phases precession in two coherently precessing domains. It is the response of the current to the phase between two weakly connected regions of coherent quantum states cite{YuM}. It was described by Josephson in [2]. We use the SU(3) Schwinger's boson theory to study the spin transport properties in the twodimensional anisotropic frustrated Heisenberg model in the triangular lattice at T=0. We have investigated the behavior of the spin conductivity for this model which presents an single-ion anisotropy. We study the spin transport in the Bose-Einstein condensation regime where we have that the tz bosons are condensed and the following condition is valid: 〈t z 〉=t . Our results show a metallic spin transport for ω>0 and a superfluid spin transport in the limit of DC conductivity, ω→0 , where σ(ω) tends to infinity in this limit of ω. [1] Yu. M. Bunkov, G. E. Volovik, Novel Superfluids, eds. K. H. Bennemann and J. B. Ketterson, Oxford University press, arXiv:1003.4889v3 (2013). [2] B. D. Josephson, Phys. Rev. Lett. 1, 251 (1962).