晶格量子涨落对spin-Peierls系统低能量激发态的影响

在非绝热近似下，研究了一维spin-Peierls系统中晶格量子涨落 对系统性质的影响，讨论了系统的二聚化相变、单粒子激发和双粒子束缚态. 结果表明，量子晶格涨落会抑制晶格的二聚化，破坏系统的spin-Peierls基态稳定性.在临界点，系统发生从二聚化spin-Peierls态向无能隙态的相变. 自旋声子耦合强度对束缚态能隙的影响比单粒子激发谱能隙显著. 关键词： sin-Peierls系统 非绝热近似 玻色化 相图

Quantum lattice dynamical effects on the low-energy excitations in spin-Peierls systems

Using the bosonization technique and Gaussian wave functional method, we investi gate the low-energy excitations of a spin-Peierls chain where the spins interact with quantum phonons. The results show that the energy gap of the one- and two- particle excitation states decrease gradually when spin-phonon coupling constant decreases or the phonon frequency increases. A quantum phase transition from a gapless spin-fluid phase to a gapped dimerized phase occurs at a nonzero critica l value of the spin-phonon coupling. Our results indicate that the two-particle excitation spectrum is much more sensitive to spin-phonon coupling constant than the one-particle excitation spectrum.