Spin-polarized transport in Aharonov–Bohm rings with impurities: A scattering-matrix approach

We present a scattering-matrix approach to electron transport through a mesoscopic ring pierced by a magnetic field, containing a magnetic impurity plus an arbitrary number of defects. Our approach entails a suitable extension of the ★‐product composition rule for the scattering matrix in quasi-one-dimensional systems. As an application of the method, we analyze the Aharonov–Bohm oscillations of the transmission coefficients as the strength or the number of the defects is varied. The method can be straightforwardly generalized to periodic arrays of Aharonov–Bohm rings.