自旋为1/2的亚铁磁棱型X-Y链的内能

利用不变本征算符法计算低温下自旋为1/2的一维亚铁磁棱型X-Y链系统的元激发谱,并讨论在此系统中不同特殊情形下的元激发能量.推导出体系的3个临界磁场强度(H C1,H C2,H Peak).讨论当外磁场HH C1或HH C2时,体系出现能隙;当H C1HH C2时体系不出现能隙的物理机制.体系的内能随外加磁场的增加逐渐减少,随温度的升高逐渐增大.绝对零度下,在高外磁场区二聚体分子内电子自旋平行排列的铁磁交换作用能J F与二聚体与单基体分子间电子自旋反平行排列的反铁磁交换作用能J AF之比(-J F/J AF)对体系的内能几乎无影响.但在有限温度,大外磁场下时,曲线重合出现分裂迹象.

Internal Energy of Ferrimagnetic Diamond X-Y Chain of Spin-l/2

The elementary excitation spectra of the one-dimensional spin-1/2 X-Y model in the ferri- magnetic diamond chain at low temperature were calculated by using IEO method in this paper. And the elementary excitations energy was discussed under different situations. Therefore, the analytic solutions of the three critical magnetic field intensity Hcl, Hc2, Hpeak were given. When the external magnetic field H 〈 Hc1 or H 〉 Hc2, energy gap could appear in the system; and when Hcl 〈 H 〈 Hc2, energy gap did not ap- pear in the system. This physical mechanism was discussed. Internal energy of the system reduced gradually as the external magnetic field increased, or increased as the temperature rose. The ratio （ -JF/JAF ） of the JF （ the intramolecular ferromagnetic exchange interaction energy leading to parallel alignments of electron spins within the dimers） and the JAF （ the intermolecular anti-ferromagnetic exchange interaction ener- gy leading to anti-parallel alignments of electron spins between monomers and dimers）, almost had no effect on internal energy of the system in the high external magnetic field at absolute zero. But, superposi- tion of the curve split in the higher external magnetic field at the finite temperature.