Articles dans des revues à comité de lecture
|The McCoy-Wu model in the mean-field approximation|
|Berche B., Berche P.E., Igloi F., Palagyi G.|
|Journal of Physics A: Mathematical and General 31 (1998) 5193|
|DOI : 10.1088/0305-4470/31/23/003|
|ArXiv : cond-mat/9804132 [PDF]|
We consider a system with randomly layered ferromagnetic bonds (McCoy-Wu model) and study its critical properties in the frame of mean-field theory. In the low-temperature phase there is an average spontaneous magnetization in the system, which vanishes as a power law at the critical point with the critical exponents Î² âo/oo^ 3.6 and Î²1 âo/oo^ 4.1 in the bulk and at the surface of the system, respectively. The singularity of the specific heat is characterized by an exponent Î± âo/oo^ -3.1. The samples reduced critical temperature tc = Tavc - Tc has a power law distribution P(tc) â^¼ tÏo/ooc and we show that the difference between the values of the critical exponents in the pure and in the random system is just Ïo/oo âo/oo^ 3.1. Above the critical temperature the thermodynamic quantities behave analytically, thus the system does not exhibit Griffiths singularities.