Generation and manipulation of pure spin current in a conducting loop coupled to an Aharonov-Bohm ring.

In this work we put forward a new prescription for the generation and manipulation of non-decaying pure spin current in a Rashba
spin-orbit (SO) coupled conducting loop which is attached to an Aharonov-Bohm (AB) ring. In presence of a single link between the
rings, a spin current is established in the flux-free ring, without accompanying any charge current. The magnitude and direction
of this spin current are controlled by means of the AB flux, without tuning the SO coupling, which is the central aspect of our
study. Employing a tight-binding (TB) framework we describe the two-ring quantum system, where the effect of magnetic flux is
incorporated through Peierls phase factor. The specific roles of AB flux, SO coupling and the connectivity among the rings are
critically investigated which yield several non-trivial signatures in energy band spectrum and pure spin current. Along with spin
current, the phenomenon of flux-driven charge current is also discussed, and at the end, different other effects like electron
filling, system size and disorder are analyzed to make the present communication a self contained one. Our detailed investigation
may provide some key aspects of designing efficient spintronic devices where spin current can be guided in an other way.