A magnetic barrier in confined two-dimensional electron gases: Nanomagnetometers and magnetic switches

We investigate the conductance properties of a hybrid ferromagnet-semiconductor structure consisting of a confined two-dimensional electron gas and a transverse ferromagnetic strip on top. Within the framework of the Landauer-B\"uttiker model, we develop an alternative way to consider magnetic fields. Our method describes devices ranging from a recently realized nanomagnetometer down to quasi one-dimensional quantum wires. We provide a rigorous way to relate the measured resistance to the actual magnetization of the strip. Regarding the quasi one-dimensional wires we propose a new device application, a tunable magnetic switch.Comment: 4 pages, 5 figures included, to be published in Applied Physics Letter

Adiabatic charge and spin pumping through quantum dots with ferromagnetic leads

We study adiabatic pumping of electrons through quantum dots attached to ferromagnetic leads. Hereby we make use of a real-time diagrammatic technique in the adiabatic limit that takes into account strong Coulomb interaction in the dot. We analyze the degree of spin polarization of electrons pumped from a ferromagnet through the dot to a nonmagnetic lead (N-dot-F) as well as the dependence of the pumped charge on the relative leads' magnetization orientations for a spin-valve (F-dot-F) structure. For the former case, we find that, depending on the relative coupling strength to the leads, spin and charge can, on average, be pumped in opposite directions. For the latter case, we find an angular dependence of the pumped charge, that becomes more and more anharmonic for large spin polarization in the leads.Comment: 9 pages, 7 figures, published in Phys. Rev.