Spin-Polarized Transport Through a Quantum Dot Coupled to Leads with Spin-Dependent Electron Temperature

Abstract

We study the effect of a spin-dependent electron temperature detected in a recent experiment on the electronic transport through a quantum dot connected to external leads. At low temperatures, the electron occupation number on the dot and the current become fully spin-polarized even in the presence of a weak temperature difference between spin-up and spin-down electrons. With rising temperature, the spin information will be overwhelmed by the electrons’ thermal motion. Under an applied magnetic field, the resonances in the spin-up and spin-down currents are separated and then a 100 % spin-polarized current emerges. Now the device operates as a spin filter. It is also found that the magnitude of the current’s spin polarization can be obviously enhanced by properly adjusting the left–right asymmetry of the dot–lead coupling strengths.