The principle of a novel device, which is called a superconducting spin switch or a spin valve for supercurrent, is proposed and theoretically justified. It is based on a four-layer antiferromagnet/ferromagnet/superconductor/ferromagnet spin-valve-like structure. Calculations show that this structure has either zero value or lower superconducting transition temperature for the parallel alignment of magnetizations in the ferromagnetic layers as compared with an antiparallel alignment of magnetizations. Thus, the supercurrent flowing through the superconducting layer can be switched by rotating the magnetization of the top free ferromagnetic layer by a weak external magnetic field.

• Received 18 May 1998

DOI:https://doi.org/10.1103/PhysRevLett.83.2058