Quantum interference and Coulomb correlation effects in spin-polarized transport through two coupled quantum dots

Abstract

Spin-dependent transport through two coupled single-level quantum dots attached to ferromagnetic leads with collinear (parallel and antiparallel) magnetizations is analyzed theoretically by the nonequilibrium Green function technique. Transport characteristics, in particular, linear and nonlinear differential conductance and tunnel magnetoresistance associated with the magnetization rotation from antiparallel to parallel alignment, are calculated numerically with intradot Coulomb interaction taken into account. The relevant Green functions are derived by the equation of motion method within the Hartree-Fock decoupling scheme. The dot occupations and Green functions are calculated self-consistently, and the numerical analysis is focused on the interference (Fano antiresonance) and Coulomb interaction effects. It is shown that the presence of Fano antiresonance depends on the sign of the nondiagonal coupling elements.