The flavour liquid state and Hund's rule effects in spin systems with orbital degeneracy

• 来源期刊: 中国物理（英文版）
• 学科: 物理学
• 关键词: SU(4) symmetry Hund's rule flavour liquid state ordered state
• 年，卷（期）: 2002,（8）
• 页码范围: 817-822
• 页数: 6页
• 分类号: O4
• 语种: 英文

摘要

In order to understand the properties of the spin system with orbital degeneracy, we first generalize the linearizedsemiclassical spin wave method for the SU(2) generators into the SU(4) case, and then investigate the elementary exci-tations of the orbital-spin systems in the SU(4) limit. The results show that, due to the reduction of the dimensionalityof the excitations, the ordered state of the SU(4) spin-orbital model is unstable. Secondly, we study the effects of theHund interaction on the flavour liquid state of the system. Our mean-field results suggest that, for a small Hund inter-action, the flavour liquid state is still stable against the generalized spin-density wave state, but with sufficient deviationfrom the SU(4) limit, the long-range order may be attained in two-dimensional systems. Finally, the implications forthe experimental observations on the material LiNiO2 are discussed.