双模随机晶体场对混合自旋1/2和自旋1纳米管上相变的影响

Effects of bimodal random crystal field on the phase transition of mixed spin-1/2 and spin-1 on nanotube

摘要:

本文利用有效场理论研究了自旋1/2和自旋1混合Blume-Capel模型在具有双模随机晶体场的圆柱形Ising纳米管上的磁化和相变. 通过数值计算，我们得到了随温度和随机晶体场参数变化的相图和磁化强度. 结果表明: (1) 改变晶体场的概率和比例，双模随机晶体场可以描述不同掺杂原子对自旋的作用；(2) 对于一定的概率值、负或正的晶体场和晶体场的比例值都存在临界点；(3) 系统显示多种相变温度，一阶相变和二阶相变.

Abstract:

The magnetization and phase transition of mixed spin-1/2 and spin-1 Blume-Capel model on a cylindrical Ising nanotube with bimodal random crystal fields were investigated by using the effective field theory. Employing numerical calculation, the phase diagrams and the magnetization which depends on the temperature and the parameters of random crystal fields were obtained. The results show that: (1) Changing the probability and the ratio of the crystal fields, bimodal random crystal fields may describe different doped atoms acting on spins. (2) The critical points do exist for certain values of the probability, the negative or positive crystal field and the ratio of the crystal fields. (3) The system shows several phase transition temperatures, first-order and second-order phase transitions.