Multistability and its influence on temperature-induced ratchet currents in inertial Brownian motors

We investigate the ratchet current (RC) in an inertial Brownian particle under the variation of mass, driving parameters, ratchet asymmetry, and temperature, modeled via the noise intensity (Q). Using stochastic simulations combined with parameter-space analysis, we show that the RC is strongly influenced by dynamical regimes, including periodic motion, chaos, bifurcations, and, most important, multistability. Notably, multistability plays a central role in the generation of temperature-induced RCs. The inclusion of Gaussian noise with arbitrarily small values of Q triggers transitions between coexisting deterministic attractors, leading to a preference for specific states. This noise-induced selection mechanism breaks velocity-space symmetry and enables directed transport. Lyapunov spectra, basins of attraction, and trajectory comparisons confirm that multistable regimes are the fundamental source of RC induced by noise. A global temperature analysis further reveals minimal RC at low Q, enhancement at intermediate Q, and suppression at high Q, while positive directed transport persists for small particle masses. These findings highlight the critical role of noise-driven transitions in deterministic multistable systems as a mechanism for controlling stochastic transport.