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

We investigate the conductance properties of a hybrid ferromagnet-semicondu ctor structure consisting of a confined two-dimensional electron gas and a transverse ferromagnetic strip on top. Within the framework of the Landauer -Buttiker model, we develop an alternative way to consider magnetic fields. Our method describes devices ranging from a recently realized nanomagnetom eter 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 device application , a tunable magnetic switch. (C) 2000 American Institute of Physics. [S0003 -6951(00)01146-3].