中国物理B ›› 2015, Vol. 24 ›› Issue (5): 56701-056701.doi: 10.1088/1674-1056/24/5/056701

• CONDENSED MATTER: STRUCTURAL, MECHANICAL, AND THERMAL PROPERTIES • 上一篇    下一篇

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

李若言a, 贺亮b, 孙青c, 纪安春c, 田光善a   

  1. a School of Physics, Peking University, Beijing 100048, China;
    b Institut für Theoretische Physik, Leopold-Franzens Universität Innsbruck, A-6020 Innsbruck, Austria;
    c Department of Physics, Capital Normal University, Beijing 100048, China
  • 收稿日期:2014-11-08 修回日期:2014-12-26 出版日期:2015-05-05 发布日期:2015-05-05
  • 基金资助:

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

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

Li Ruo-Yan (李若言)a, He Liang (贺亮)b, Sun Qing (孙青)c, Ji An-Chun (纪安春)c, Tian Guang-Shan (田光善)a   

  1. a School of Physics, Peking University, Beijing 100048, China;
    b Institut für Theoretische Physik, Leopold-Franzens Universität Innsbruck, A-6020 Innsbruck, Austria;
    c Department of Physics, Capital Normal University, Beijing 100048, China
  • Received:2014-11-08 Revised:2014-12-26 Online:2015-05-05 Published:2015-05-05
  • Contact: Sun Qing, Ji An-Chun E-mail:sunqing@cnu.edu.cn;andrewjee@sina.com
  • About author:67.85.-d; 37.10.Jk; 71.10.Fd
  • Supported by:

    Project 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.

关键词: ultracold Fermi gas, optical lattice, spin–, orbit coupling, spin excitation spectrum

Abstract:

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.

Key words: ultracold Fermi gas, optical lattice, spin–, orbit coupling, spin excitation spectrum

中图分类号:  (Ultracold gases, trapped gases)

  • 67.85.-d
37.10.Jk (Atoms in optical lattices) 71.10.Fd (Lattice fermion models (Hubbard model, etc.))