Effective field theory for the Ising model with a fluctuating exchange integral in an asymmetric bimodal random magnetic field: A differential operator technique

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• 作者：Ioannis A. Hadjiagapiou ; ^{ihatziag@phys.uoa.gr}
• 关键词：Ising model ; Fluctuating pair interactions ; Asymmetric bimodal random field ; Effective field theory ; Phase diagram ; Phase transitions ; Magnetization
• 刊名：Physica A
• 出版年：2013
• 出版时间：1 March, 2013
• 年：2013
• 卷：392
• 期：5
• 页码：1063-1071
• 全文大小：410 K

文摘

The spin-1/2 Ising model on a square lattice, with fluctuating bond interactions between nearest neighbors and in the presence of a random magnetic field, is investigated within the framework of the effective field theory based on the use of the differential operator relation. The random field is drawn from the asymmetric and anisotropic bimodal probability distribution , where the site probabilities take on values within the interval with the constraint ; is the random field variable with strength and the competition parameter, which is the ratio of the strength of the random magnetic field in the two principal directions and ; is considered to be positive resulting in competing random fields. The fluctuating bond is drawn from the symmetric but anisotropic bimodal probability distribution , where and represent the average value and standard deviation of , respectively. We estimate the transition temperatures, phase diagrams (for various values of the system¡¯s parameters ), susceptibility, and equilibrium equation for magnetization, which is solved in order to determine the magnetization profile with respect to and .