Spin filtering implemented through Rashba and weak magnetic modulations

We present two theoretical schemes for spin filters in one-dimensional semiconductor quantum wires with spatially modulated Rashba spin-orbit coupling (SOC) as well as weak magnetic potential. For case I, the SOC is periodic and the weak magnetic potential is applied uniformly along the wire. Full spin polarizations with opposite signs are obtained within two separated energy intervals. For case II, the weak magnetic potential is periodic while the SOC is uniform. An ideal negative/positive switching effect for spin polarization is realized by tuning the strength of SOC. The roles of SOC, magnetic potential, and their coupling on the spin filtering are analyzed.Comment: 4 pages, 4 figure

Research on 2×2 MIMO Channel with Truncated Laplacian Azimuth Power Spectrum

Multiple-input multiple-output (MIMO) Rayleigh fading channel with truncated Laplacian azimuth power spectrum (APS) is studied. By using the power correlation matrix of MIMO channel model and the modified Jakes simulator, into which with random phases are inserted, the effect of the azimuth spread (AS), angle of departure (AOD) and angle of arrival (AOA) on the spatial correlation coefficient and channel capacity are investigated. Numerical results show that larger AS generates smaller spatial correlation coefficient amplitude, while larger average AOD or AOA produces larger spatial correlation coefficient amplitude. The average capacity variation is comprehensively dominated by the average AOD, AOA and AS

Ideal switching effect in periodic spin-orbit coupling structures

An ideal switching effect is discovered in a semiconductor nanowire with a spatially-periodic Rashba structure. Bistable `ON' and `OFF' states can be realized by tuning the gate voltage applied on the Rashba regions. The energy range and position of `OFF' states can be manipulated effectively by varying the strength of the spin-orbit coupling (SOC) and the unit length of the periodic structure, respectively. The switching effect of the nanowire is found to be tolerant of small random fluctuations of SOC strength in the periodic structure. This ideal switching effect might be applicable in future spintronic devices.Comment: 4 pages and 4 figure