Spin excitation spectra of spin–orbit coupled bosons in an optical lattice  

作　　者：李若言 贺亮 孙青 纪安春 田光善 

机构地区：[1]School of Physics, Peking University [2]Institut für Theoretische Physik, Leopold-Franzens Universitat Innsbruck [3]Department of Physics, Capital Normal University

出　　处：《Chinese Physics B》2015年第5期451-459,共9页中国物理B（英文版）

基　　金：supported by the National Natural Science Foundation of China(Grant Nos.11347197,11404225,and 11474205)

摘　　要：Spin-wave excitation plays important roles in the investigation of the magnetic phases. In this paper, we study the spin-wave excitation spectra of two-component Bose gases with spin-orbit coupling in a deep square optical lattice using the spin-wave theory. We find that, while the excitation spectrum of the vortex crystal phase is gapless with a linear dispersion in the vicinity of the minimum point, the spectra of the commensurate spiral spin phase and the skyrmion crystal phase are gapped. Significantly, the spin fluctuations strongly destabilize the classical ground state of the skyrmion phase with the appearance of an imaginary part in the eigenfrequencies of spin excitations. Such features of the spin excitation spectra provide further insights into the exotic spin phases.Spin-wave excitation plays important roles in the investigation of the magnetic phases. In this paper, we study the spin-wave excitation spectra of two-component Bose gases with spin-orbit coupling in a deep square optical lattice using the spin-wave theory. We find that, while the excitation spectrum of the vortex crystal phase is gapless with a linear dispersion in the vicinity of the minimum point, the spectra of the commensurate spiral spin phase and the skyrmion crystal phase are gapped. Significantly, the spin fluctuations strongly destabilize the classical ground state of the skyrmion phase with the appearance of an imaginary part in the eigenfrequencies of spin excitations. Such features of the spin excitation spectra provide further insights into the exotic spin phases.

关 键 词：ultracold Fermi gas optical lattice spin-orbit coupling spin excitation spectrum 

分 类 号：O433[机械工程—光学工程]