  In the present work the possibility of regulating local magnetic field in a
quantum ring is investigated theoretically. The ring is coupled to a quantum
wire and subjected to an in-plane electric field. Under a finite bias voltage
across the wire a net circulating current is established in the ring which
produces a strong magnetic field at its centre. This magnetic field can be
tuned externally in a wide range by regulating the in-plane electric field, and
thus, our present system can be utilized to control magnetic field at a
specific region. The feasibility of this quantum system in designing spin-based
quantum devices is also analyzed.
