Flux pinning in multifilamentary superconducting wires with ferromagnetic artificial pinning centers

We demonstrate that ferromagnets are effective artificial pinning centers for the enhancement of critical current (J/sub c/) in multifilamentary superconducting wires. We have analyzed theoretically the proximity effect due to the FM pins near the final size of several nanometers and determined that one should achieve a large pinning force by such centers at these sizes. There is also additional pinning strength resulting from the interaction between ferromagnetic moments of the pins and the magnetic field gradient of the fluxon lattice. The measured results of J/sub c/, T/sub c/ and H/sub c2/ are analyzed, and compared with our model analysis.