Radiative cooling induced by time-symmetry breaking in periodically driven systems

We study theoretically the thermal relaxation of many-body systems under the action of oscillating external fields. When the magnitude or the orientation of a field is modulated around values where the pairwise heat-exchange conductances depend nonlinearly on this field, we demonstrate that the time symmetry is broken during the evolution of temperatures over a modulation cycle. We predict that this asymmetry enables a pumping of heat that can be used to cool the system down faster. This effect is illustrated through different magneto-optical systems under the action of an oscillating magnetic field.