Effect of spin exchange interaction on shot noise and tunnel magnetoresistance in double quantum dots

• The electron correlation is a highly focused topic of research in mesoscopic transport-systems.
• This paper demonstrates how the giant negative differential conductance can be generated by the spin exchange interaction (SEI) of two electrons.
• Moreover the SEI has great influences on the tunnel magnetoresistance and shot noise.
• It also leads to enhancement or suppression of the super-Poissonian statistics of transport electrons depending on the type of exchange couplings.

By means of the Rate equation approach in sequential tunneling regime, we study spin-polarized transport through series double quantum dots (DQD) weakly coupled to collinear ferromagnetic leads with particular attention on the effect of interdot spin exchange interaction (SEI). For the asymmetric DQD giant negative differential conductance is realized, which depends on the energy-level spacing between two dots. It is demonstrated that the voltage dependencies of the tunnel magnetoresistance (TMR) and the shot noise are sensitive to the SEI, which leads to the additional imbalance between spin-polarized currents. The super-Poissonian statistics is enhanced in the parallel leads’ configuration by the ferromagnetic SEI, which favorites the spin bunching, while it is suppressed by stronger antiferromagnetic SEI in antiparallel configuration for a symmetric DQD. The voltage dependencies of the TMR and shot noise may be used to probe the SEI.