Cooling a nanoscale device by a spin-polarized nonequilibrium current

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The ongoing miniaturization of electronic devices and the concomitant increase of the processing speed pose perpetual challenges to the cooling of technological devices. On the macroscale, demagnetization cooling based on magnetocaloric effects in bulk materials is a successful tool to remove undesired heat from an object. In this proposal, we transfer the basic idea to the nanoscale by exploring the quantum mechanical exchange coupling of a spin-polarized electron current in a quantum transport set-up to the local magnetization of a magnetic nanoobject to be cooled. Since inevitable electric losses in the transport set-up give rise to Ohmic heating, the nonequilibrium dynamics of local phonon modes has to be addressed on the same footing such that a net cooling results. This project aims at working out the details of such a “nanorefrigerator” which is expected to work under nonequilibrium conditions, presumably at an optimal working point. Under such conditions, both of the countercurrent effects of the spin cooling and the Ohmic heating can be expected to be optimally under control.