Three-dimensional nonequilibrium Potts systems with magnetic friction.
We study the nonequilibrium steady states that emerge when two interacting three-dimensional Potts blocks slide on each other. As at equilibrium the Potts model exhibits different types of phase transitions for different numbers q of spin states, we consider the following three cases: q=2 (i.e., the Ising case), q=3, and q=9, which at equilibrium yield, respectively, a second-order phase transition, a weak first-order transition, and a strong first-order transition. In our study we focus on the anisotropic character of the steady states that result from the relative motion and discuss the change in finite-size signatures when changing the number q of spin states.