Tuning a zigzag SiC nanoribbon as a thermal spin current generator

Quantum transport and spin current in a zigzag SiC nanoribbon device under a thermal gradient are investigated theoretically within the framework of the Landauer–B ü ttiker formalism using a first-principles technique. It is found that the edge state transport channels can be turned off or kept open by specific edge doping, and different spin channels can be controlled separately. Interestingly, by replacing an edge C atom with a B atom and an edge Si atom with a P atom in the scattering region, a Seebeck thermopower with different signs for different spins and a finite conductance for both spins can be obtained in the linear response regime. The subsequent thermoelectric field drives electrons of different spin channels in opposite directions, which leads unambiguously to a spin current. More importantly, by tuning the chemical potential and working temperature, pure spin current can be achieved. This provides a promising two-dimensional candidate system for producing pure spin current via the spin-dependent Seebeck effect. (paper)