%0 Journal Article
%A Fernández Pérez, Luis Antonio
%A Gordillo Guerrero, A.
%A Martín Mayor, Víctor
%A Ruiz Lorenzo, J. J.
%T First Order Phase Transition in a 3D disordered system
%D 2008
%@ 0094-243x
%U https://hdl.handle.net/20.500.14352/51917
%X We present a detailed numerical study on the effects of adding quenched impurities to a three dimensional system which in the pure case undergoes a strong first order phase transition (specifically, the ferromagnetic/paramagnetic transition of the site-diluted four states Potts model). We can state that the transition remains first-order in the presence of quenched disorder (a small amount of it) but it turns out to be second order as more impurities are added. A tricritical point, which is studied by means of Finite-Size Scaling, separates the first-order and second-order parts of the critical line. The results were made possible by a new definition of the disorder average that avoids the diverging-variance probability distributions that arise using the standard methodology. We also made use of a recently proposed microcanonical Monte Carlo method in which entropy, instead of free energy, is the basic quantity.
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