Thermal Spin Generator Based on a Germanene Nanoribbon Subjected to Local Noncollinear Exchange Fields

Spintronics relies on generating, manipulating, and detecting spin current. In addition, converting waste heat into electricity is an essential topic for current and future technologies. To explore spin caloritronics, the authors propose a thermoelectric spin-current generator, consisting of a zigzag germanene nanoribbon with thermal leads partially exposed to noncollinear exchange fields. The spin polarization of the current in the leads can reach 100%, 0%, or even \ensuremath{\infty} (pure spin current with no charge flow), but only under a temperature difference, and the giant magnetoresistance can reach extremely large values just by adjusting the relative directions of the exchange fields.