Nonequilibrium critical behavior of magnetic thin films grown in a temperature gradient

CANDIA, J; E. V. ALBANO

JOURNAL OF STATISTICAL MECHANICS-THEORY AND EXPERIMENT

IOP PUBLISHING LTD

Lugar: Londres; Año: 2012 vol. 2012 p. 8006 - 8028

1742-5468

We investigate the irreversible growth of (2 + 1)-dimensional magnetic thin lms under the inuence of a transverse temperature gradient, which is maintained by thermal baths across a direction perpendicular to the direction of growth. Therefore, dierent longitudinal layers grow at dierenttemperatures between T1 and T2, where T1 < Thom c < T2 and Thom c = 0:69(1)is the critical temperature of lms grown in homogeneous thermal baths. We nda far-from-equilibrium continuous order{disorder phase transition driven by thethermal bath gradient. We characterize this gradient-induced critical behaviorby means of standard nite-size scaling procedures, which lead to the criticaltemperature Tc = 0:84(2) and a new universality class consistent with the setof critical exponents  = 3=2,  = 5=2, and  = 1=4. In order to gain furtherinsight into the eects of the temperature gradient, we also develop a bond modelthat captures the magnetic lm´s growth dynamics. Our ndings show that theinterplay of geometry and thermal bath asymmetries leads to growth bond flux asymmetries and the onset of transverse ordering eects that explain qualitativelythe shift observed in the critical temperature. The relevance of these mechanismsis further conrmed by a nite-size scaling analysis of the interface width, whichshows that the growing sites of the system dene a self-ane interface.