Giant fluctuations of superconducting order parameter in ferromagnet-superconductor single-electron transistors.
Spin dependent transport in a ferromagnet-superconductor single-electron transistor is studied theoretically taking into account spin accumulation, spin relaxation, gap suppression, and charging effects. A strong dependence of the gap on the magnetic state of the electrodes is found, which gives rise to a magnetoresistance of up to 100%. We predict that fluctuations of the spin accumulation can play such an important role as to cause the island to fluctuate between the superconducting and normal states. Furthermore, the device exhibits a nearly complete gate-controlled spin-valve effect.
Johansson
J
J
Nanostructure Physics, Royal Institute of Technology, AlbaNova University Center, 10691 Stockholm, Sweden.
Korenivski
V
V
Haviland
D B
DB
Brataas
Arne
A