The effects of lead–ring coupling and the external Rashba interaction on the effective spin polarization of a chain of quantum nano rings

Abstract

The effective spin polarization and spin filtering of a linear chain of N one-dimensional nanorings in the presence of the Rashba and Aharonov–Bohm effects are studied by considering three different lead–ring coupling regimes. Utilizing the transfer-matrix method, the optimal number of rings for maximizing the system efficiency is determined in the weak, medium, and strong lead–ring coupling regimes. The strong coupling regime is proposed for the design of spintronic devices as it exhibits the highest system efficiency. Furthermore, by tuning the Rashba strengths in the rings alternately, perfect spin filtering and full-range spin polarization with high efficiency can be obtained in narrow ranges of the incident electron wavenumber. Moreover, controlling the Rashba strength leads to the design of energy-filtering devices with a desired spin polarization, which could play a dominant role in spintronic technology.