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We theoretically investigate the control of spin-polarized dwell time by δ-doping in a parallel double δ-magnetic-barrier nanostructure, which can be realized experimentally by depositing two asymmetric ferromagnetic stripes at the top and bottom of an InAs/Al x In1−x As heterostructure, respectively. Dwell time is still spin-polarized even if a δ-doping is included inside. Both the magnitude and the sign of the spin-polarized dwell time can be manipulated by changing the weight or position of δ-doping. Therefore, this nanostructure can be employed as a structurally controllable temporal spin splitter for spintronic device applications.

The giant magnetoresistance (GMR) effect in a device, composed of nanosized ferromagnetic (FM)-Schottky metals (SM) and semiconductor heterostructure, is investigated theoretically. Experimentally, this GMR device can be realized by the deposition of two parallel FM strips and a SM stripe on the top of a GaAs heterostructure. It is shown that the GMR effect ascribes a significant electron transmission difference between the parallel and antiparallel magnetization configurations of two FM stripes in the device. It is also shown that the magnetoresistance (MR) ratio depends strongly on the magnetic intensity of the magnetic barrier (MB) and the electric-barrier (EB) height induced by an applied voltage to the SM stripe. Thus, this device can be used as a tunable GMR one, whose MR ratio can be switched by adjusting the applied voltage under the SM stripe or by changing the magnetic strength of the MB.