Spin-resolved transport through a quantum dot driven by bias and temperature gradient

Abstract

Abstract In this paper we use a simple model to discuss spin-related currents generated by a voltage or temperature gradient in a system of a quantum dot (QD) connected with normal metal leads. The QD is designed as a model possessing spin-resolved transport channels. By applying voltage and temperature gradient separately to the system, we investigate its current behaviors in nonlinear regime. In voltage-driven case, it is shown that the system can generate spin-polarized currents. Interestingly, when Coulomb interaction is infinite, there is a correlation-induced spin current in a symmetric transport configuration. In temperature-driven case, it is found that the system can generate a thermal-induced pure spin current with zero Coulomb interaction or finite Coulomb interaction, even connected with normal metal leads. When Coulomb interaction sets in, spin correlation makes the dot’s low energy channel more competitive. The spin current or charge current show nonlinear behaviors which originates from the competition of two channels. The model demonstrates that temperature-driven QD junctions show some results different from voltage-driven junction, in which correlation or competition induced spin-resolved effects may be useful in the future design of thermal-based spintronic devices.