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Non-order parameter Langevin equation for a bounded Kardar-Parisi-Zhang universality class

By: Francisco de los Santos
From: Departamento de Electromagnetismo y Física de la Materia, Facultad de Ciencias, Granada, Espanha
At: Complexo Interdisplinar, Anfiteatro
[2005-10-19] 11.30

We introduce a Langevin equation describing the pinning-depinning phase transition experienced by Kardar-Parisi-Zhang interfaces in the presence of a bounding ``lower-wall'. This provides a continuous description for this universality class, complementary to the different and already well documented one for the case of an ``upper-wall'. The Langevin equation is written in terms of a field that is not an order-parameter, in contrast to standard approaches, and is studied both by employing a systematic mean-field approximation and by means of a recently introduced efficient integration scheme. Our findings are in good agreement with known results from microscopic models in this class, while the numerical precision is improved. This Langevin equation constitutes a sound starting point for further analytical calculations, beyond mean-field, needed to shed more light on this poorly understood universality class.