“…The expected advantages of spintronics devices are nonvolatility, higher integration densities, lower power operation and higher switching speeds. Extensive efforts have been devoted to exploring the electron-spin polarization properties in a wide variety of structures [2][3][4][5][6][7][8][9][10][11][12][13][14], such as magnetic dots [5,6], superlattices [7][8][9][10][11], wires [12,13], and transverse steps [14], which could be realized experimentally in non-planar two-dimensional electron gas (2DEG) [15,16], or by patterning ferromagnetic and superconducting materials [17]. In fact, the electron spin-dependent properties in artificial nanostructures have become one of the today's leading subjects in the physics of electronic devices.…”