Effects of bimodal random crystal field on the magnetization and phase transition of Blume-Capel model on nanotube

Abstract

Recently, the physical properties and applications of the magnetic nanotube have attracted a great deal of theoretical and experimental attention. The magnetization and phase transition of spin-1 Blume-Capel model on a cylindrical Ising nanotube with bimodal random crystal fields are investigated by using the effective field theory. Employing numerical calculations, we obtain the phase diagrams and the magnetization, which depend on the temperature and the parameters of random crystal fields. Our obtained results are as follows. (i) Changing the probability (p) and the ratio of the crystal fields (), the bimodal random crystal fields may describe different doped atoms acting on spins. Especially, for p = 0.5, choosing = 0,-1.0,-0.5 and 0.5, the bimodal random crystal fields can respectively degrade four typical distributions of random crystal fields, i. e., the distribution of diluted crystal fields, the distribution of symmetry staggered crystal fields, the distribution of non-symmetry staggered crystal fields, and the distribution of same-direction crystal field. (ii) The system exhibits different magnetic properties and phase transition behaviors in the diluted, staggered and same-direction crystal field. The diluted and staggered crystal fields may reduce the magnetization of the system, resulting in the ground state saturation value of magnetization, which is less than 1, while the same-direction crystal fields cannot result in a similar behavior. (iii) The system shows several phase transition temperatures, i.e., first-order and second-order phase transitions and reentrant phenomenon as the parameters of bimodal random crystal fields change. The tricritical point and reentrant phenomenon do exist for certain values of the probability, the negative crystal field and the ratio of the crystal fields in the system. The relevant experiment is needed to verify the above-mentioned theoretical results.