Critical behaviour of driven bilayer systems: a field-theoretic renormalization group study

We investigate the static and dynamic critical behaviour of a uniformly driven bilayer Ising lattice gas at half-filling. Depending on the strength of the inter-layer coupling J, phase separation occurs across or within the two layers. The former transitions are controlled by the universality class of model A (corresponding to an Ising model with Glauber dynamics), with upper critical dimension dc=4. The latter transitions are dominated by the universality class of the standard (single-layer) driven Ising lattice gas, with dc=5 and a nonclassical anisotropy exponent. These two distinct critical lines meet at a nonequilibrium bicritical point which also falls into the driven Ising class. At all transitions, novel couplings and dangerous irrelevant operators determine corrections to scaling. (author). Letter-to-the-editor