Electron-spin filter based on a novel magnetic nanostructure with zero average magnetic field

We theoretically investigate spin transport in a novel magnetic nanostructure with zero average magnetic field, which can be experimentally realized by depositing three ferromagnetic stripes with a vertical magnetization on top and bottom of a semiconductor heterostructure. It is shown that, the electronic transmission is spin dependent, though the magnetic field is averagely vanishing, i.e., this device shows an obvious spin polarization effect. It is also shown that the degree of spin polarization depends on the incident energy and the incident direction of the electron. Therefore, such a magnetic nanostructure may be used as a spin filter for spintronics applications.