Noise crosscorrelations can induce instabilities in coupled driven models

We study the effects of noise cross-correlations on the steady states of driven, nonequilibrium systems, which are described by two stochastically driven dynamical variables, in one dimension. We use a well-known stochastically driven coupled model with two dynamical variables, where one of the variables is autonomous being independent of the other, whereas the second one depends explicitly on the former. Introducing cross-correlations of the two noises in the two dynamical equations, we show that depending upon the details of the nonlinear coupling between the dynamical fields, such cross-correlations can induce instabilities in the models, that are otherwise stable in the absence of any cross-correlations. We argue that this is reminiscent of the roughening transition found in the Kardar-Parisi-Zhang equation in dimensions greater than two. Phenomenological implications of our results are discussed.