Tunneling resonances and Andreev reflection through an interaction quantum dot coupled with two half metals and a superconductor

摘要

We investigate the transport characteristics of electrons through a quantum dot with two semi-infinite half metal (HM) leads and a superconductor by the use of the equivalent single-particle multichannel network technique that takes into account the multilevel structure and the Coulomb interactions on the dot, pairing potential on the superconducting side and the exchange field on the HM side. The transport properties depend on the interplay between the Coulomb blockade effect and Andreev reflection (AR). It is found that at finite temperatures and small bias the current versus the gate voltage exhibits a series of peaks, due to the AR, depending on the resonances controlled by the charging energy and level spacing of the dot. In the case of single occupation for the quantum dot, the current of the system can be enhanced or suppressed by the exchange field.