The Study On The Electron Shin Transport In One-Dimensional Quantum Waveguides

Spintronics was first introduced in 1988 when Fert and Gruenberg independently discovered giant magnetoresistance effect(GMR).Spintronics is a new branch of condensed-matter physics devoted to studies on the manipulation of the spin degree of freedom in solids.In semiconductor spintronics,the spin-orbit interaction(SOl) offers an electric pathway to manipulate the electron spin.In chapter 1,we give a brief introduction to the electron properties in low dimensional structures,giant magnetoresistance(GMR),the development of spintronics,spin-orbit interaction,electron spin injection and spintronics device applications.In chapter 2,we investigate spin-dependent transport properties of a single-channel planar electron waveguide under a periodic modulation of Rashba SOI and subject to a weak in-plane magnetic field B_in.In a two-terminal SOI quantum wire system,the SOI alone cannot generate a spin-polarized transmitted electron beam when the output lead supports only one orbital channel.It has been shown theoretically that a remarkable spin polarization can be achieved when the time-reversal symmetry is broken by the application of a proper weak magnetic field.The spatially periodic variation in the Rashba SOI strength gives rise to a band structure with full band gaps.The inclusion of B_in with a proper orientation angleθ(relative to the transport direction) introduces local band gaps where only two propagating(one right going and one left going)modes exist.As a result,for a finite superlattice with a sufficient number of periodic units,the generated spin polarization and its direction depend strongly onθ.For a given Fermi energy higher than the Zeeman potential,there may exist several intervals ofθwithin which an optimal spin polarization is achieved.