Temperature interfaces in the Katz-Lebowitz-Spohn driven lattice gas

We explore the intriguing spatial patterns that emerge in a two-temperature Katz-Lebowitz-Spohn (KLS) model in two dimensions, a driven lattice gas with attractive nearest-neighbor interactions and periodic boundary conditions.The domain is split into two regions with hopping rates governed by different temperatures T > Tc and Tc, respectively, where Tc indicates the critical temperature for phase ordering. When the temperature boundaries are oriented transverse to the drive, the hotter region experiences an unexpected phase separation caused by the lower sustained current in the cooler region. The resulting density profiles in both hot and cold subsystems are similar to the well-characterized coexistence and maximal-current phases in (T)ASEP models with open boundary conditions, yet display marked fluctuation corrections. In contrast, when the temperature boundaries are oriented along the drive, the KLS dynamics is crucially determined by the choice of hopping rates across the temperature interfaces. In particular, when the latter break particle-hole symmetry, we observe particle influx from the cooler into the hotter region.