Active magneto gyrator as a tunable heat engine or heat pump

Abstract

We theoretically investigate the thermodynamic performance characteristics of an active magneto-gyrator taking into account the two-dimensional motion of an inertial charged active particle confined in an asymmetric parabolic potential and in contact with two heat baths kept at two different temperatures. A magnetic field of constant magnitude is applied in a direction perpendicular to the plane of motion. In such a system, the particle exhibits a gyrating motion across the potential minimum and exerts a torque on the confining potential as long as there is a potential asymmetry and temperature gradient. Hence, this system can operate as an active magneto-heat engine or pump in the presence of a load force. Interestingly, we observe that the activity or self-propulsion impacts the thermodynamic performance characteristics of the gyrator only in the presence of the magnetic field. We examine two scenarios: first, by applying a load in a direction opposing the torque and second, by applying a load in the same direction as that of torque. In the first case, for a fixed parameter regime, the gyrator is found to act as a heat engine or a heat pump depending on the strength of the applied load, whereas in the latter case, it can only operate as a heat pump. Moreover, unlike the Brownian gyrator or Brownian magneto gyrator, captivatingly, the efficiency is found to have no universal upper bound and can be made $100\%$ by tuning the system parameters. Additionally, when the system is suspended in a viscoelastic medium characterized by the presence of a finite memory, for a short persistence of memory and a fixed duration of activity, the efficiency can be $100\%$ even for more than one value of viscoelastic memory timescale.