自旋派尔斯链热力学性质研究

摘要

结合热相干态近似和玻色化技术,扩展应用量子自洽理论讨论了低温下自旋派尔斯链的磁性激发和热力学性质.研究发现自旋激发能隙随温度升高而单调下降,于派尔斯相变点(Tp)消失,在Tp附近,比热随温度升高而迅速增强.Tp的标度关系符合Tp∝δ(0)0.66.%Combining the thermal coherent states with the bosonization technique,we develop a self-consistent quantum approach to investigate the dimerized antiferromagnetic Heisenberg chain at finite temperature. In the case of weak dimerization, temperature dependences of the magnetic excited energy gap and the specific heat are calculated analytically. The energy gap monotonically decreases with increasing temperature until it vanishes at the Peierls transition temperature Tp. The specific heat is strongly enhanced near Tp. It is also found that there is a scaling behavior of Tp as a function of the zero-temperature dimerization δ0 as Tp∝δ0v with v = 0.66 for small δ0. Our results are qualitatively consistent with experimental data observed in CuGeO3.