A magnetoresistance (MR) device was proposed by depositing two parallel ferromagnetic stripes on top and bottom of a semiconductor heterostructure. In order to manipulate its performance, we dope a tunable δ-potential into the device by atomic layer doping technique. Transmission, conductance and MR ratio are calculated for the δ-doped MR device. It is confirmed that an obvious MR effect still exists in the device even though a δ-doping is comprised. Results show that the MR ratio varies intensely with the weight and/or the position of the δ-doping. Therefore, one can manip- ulate structurally the MR device by altering the δ-doping, and a tunable MR device can be obtained for magnetic information storage.
