Abstract
In layered ferromagnet-superconductor-ferromagnet structures, the critical temperature of the superconductors depends on the magnetic orientation of the ferromagnetic layers and relative to each other. So far, the experimentally observed magnitude of change in for structures utilizing weak ferromagnets has been 2 orders of magnitude smaller than is expected from calculations. We theoretically show that such a discrepancy can result from the asymmetry of F/S boundaries, and we test this possibility by performing experiments on structures where and are independently varied. Our experimental results indicate that asymmetric boundaries are not the source of the discrepancy. If boundary asymmetry is causing the suppressed magnitude of changes, it may only be possible to detect in structures with thinner ferromagnetic layers.
- Received 13 December 2007
DOI:https://doi.org/10.1103/PhysRevB.77.184501
©2008 American Physical Society