Magnetocaloritronic nanomachines

We introduce and study a magnetocaloritronic circuit element based on a domain wall that can move under applied voltage, magnetic field and temperature gradient. We draw analogies between Carnot machines and possible devices employing such a circuit element. We propose a realization of magnetocaloritronic cooling and point out the parallels between the operational principles of magnetocaloritronic and thermoelectric cooling and power generation. Following this analogy, we introduce a magnetocaloritronic figure of merit that encodes information about the maximum efficiency of such devices. Even though the magnetocaloritronic figure of merit turns out to be very small for transition-metal based magnets, we speculate that larger numbers may be expected in ferromagnetic insulators.