Thermal spin current from a ferromagnet to silicon by Seebeck spin tunnelling

A spin equivalent of the Seebeck effect is known in various metallic, insulating and semiconductor ferromagnets. In this spin effect, a temperature difference over a ferromagnetic strip leads to a spin voltage, where spin-up electrons accumulate on one side of the strip and spin-down electrons gather on the other. Le Breton et al. now report a rather different phenomenon, in which a thermal gradient over a ferromagnet/oxide/silicon device drives Seebeck electron spin tunnelling through an oxide barrier. This indicates a new mechanism for spin injection into a non-magnetic semiconductor as well as for a functional use of heat in spintronics devices.