Spin filtering in a Rashba–Dresselhaus–Aharonov–Bohm double-dot interferometer

Abstract

We study the spin-dependent transport of spin-1/2 electrons through an\ninterferometer made of two elongated quantum dots or quantum nanowires, which\nare subject to both an Aharonov-Bohm flux and (Rashba and Dresselhaus)\nspin-orbit interactions. Similar to the diamond interferometer proposed in our\nprevious papers [Phys. Rev. B {\\bf 84}, 035323 (2011); Phys. Rev. B {\\bf 87},\n205438 (2013)], we show that the double-dot interferometer can serve as a\nperfect spin filter due to a spin interference effect. By appropriately tuning\nthe external electric and magnetic fields which determine the Aharonov-Casher\nand Aharonov-Bohm phases, and with some relations between the various hopping\namplitudes and site energies, the interferometer blocks electrons with a\nspecific spin polarization, independent of their energy. The blocked\npolarization and the polarization of the outgoing electrons is controlled\nsolely by the external electric and magnetic fields and do not depend on the\nenergy of the electrons. Furthermore, the spin filtering conditions become\nsimpler in the linear-response regime, in which the electrons have a fixed\nenergy. Unlike the diamond interferometer, spin filtering in the double-dot\ninterferometer does not require high symmetry between the hopping amplitudes\nand site energies of the two branches of the interferometer and thus may be\nmore appealing from an experimental point of view.\n