Manipulation of spin filtering effect in a hybrid magnetic–electric-barrier nanostructure with a δ-doping

By means of a hybrid magnetic–electric barrier (MEB) on the top of the semiconductor InAs/AlxIn1−xAs heterostructure, a spin filter can be obtained. In this work, we introduce a δ-doping into this MEB device by molecular beam epitaxy or metal-organic chemical-vapor deposition, to manipulate the spin filtering. With the help of the improved transfer-matrix method and Landauer–Bűttiker theory, transmission coefficient, conductance and spin polarization are calculated for the electrons across this device. Due to spin-field interaction between electron spins and magnetic fields, an obvious spin filtering effect remains in the device even if a δ-doping is included inside. The behavior of spin-polarized electrons is related closely to the δ-doping, due to the strong dependence of the effective potential experienced by the electrons on such a doping. Degree of spin polarization can be manipulated by properly adjusting weight or position of the δ-doping, which gives rise to a structurally controllable spin filter.