M. H. S. Amin, et al.

A theory is offered for a novel device, mesoscopic four-terminal SQUID. The studied system consists of a mesoscopic four-terminal junction, one pair of terminals of which is incorporated in a superconducting ring and the other one is connected with a transport circuit. The nonlocal weak coupling between the terminals leads to effects of phase dragging and magnetic flux transfer. The behavior of a four-terminal SQUID, controlled by the external parameters, the applied magnetic flux, and the transport current is investigated. The critical current and the current-voltage characteristics as functions of magnetic flux are calculated. In the nonlocal mesoscopic case, they depend not only on the magnitude of the applied flux but also on its sign, allowing measurement of the direction of the external magnetic field.