| Autor: |
Talantsev EF; M.N. Mikheev Institute of Metal Physics, Ural Branch, Russian Academy of Sciences, 18, S. Kovalevskoy St, Ekaterinburg, 620108, Russia. evgeny.f.talantsev@gmail.com.; NANOTECH Centre, Ural Federal University, 19 Mira St., Еkaterinburg, 620002, Russia. evgeny.f.talantsev@gmail.com., Strickland NM; Robinson Research Institute, Victoria University of Wellington, 69 Gracefield Road, Lower Hutt, 5010, New Zealand., Wimbush SC; Robinson Research Institute, Victoria University of Wellington, 69 Gracefield Road, Lower Hutt, 5010, New Zealand.; The MacDiarmid Institute for Advanced Materials and Nanotechnology, Victoria University of Wellington, P O Box 600, Wellington, 6140, New Zealand., Brooks J; Robinson Research Institute, Victoria University of Wellington, 69 Gracefield Road, Lower Hutt, 5010, New Zealand., Pantoja AE; Robinson Research Institute, Victoria University of Wellington, 69 Gracefield Road, Lower Hutt, 5010, New Zealand., Badcock RA; Robinson Research Institute, Victoria University of Wellington, 69 Gracefield Road, Lower Hutt, 5010, New Zealand., Storey JG; Robinson Research Institute, Victoria University of Wellington, 69 Gracefield Road, Lower Hutt, 5010, New Zealand.; The MacDiarmid Institute for Advanced Materials and Nanotechnology, Victoria University of Wellington, P O Box 600, Wellington, 6140, New Zealand., Tallon JL; Robinson Research Institute, Victoria University of Wellington, 69 Gracefield Road, Lower Hutt, 5010, New Zealand.; The MacDiarmid Institute for Advanced Materials and Nanotechnology, Victoria University of Wellington, P O Box 600, Wellington, 6140, New Zealand. |
| Abstrakt: |
Recently, we showed that the self-field transport critical current, I c (sf), of a superconducting wire can be defined in a more fundamental way than the conventional (and arbitrary) electric field criterion, E c = 1 μV/cm. We defined I c (sf) as the threshold current, I c,B , at which the perpendicular component of the local magnetic flux density, B ⊥ , measured at any point on the surface of a high-temperature superconducting tape abruptly crosses over from a non-linear to a linear dependence with increasing transport current. This effect results from the current distribution across the tape width progressively transitioning from non-uniform to uniform. The completion of this progressive transition was found to be singular. It coincides with the first discernible onset of dissipation and immediately precedes the formation of a measureable electric field. Here, we show that the same I c,B definition of critical currents applies in the presence of an external applied magnetic field, B a . In all experimental data presented here I c,B is found to be significantly (10-30%) lower than I c,E determined by the common electric field criterion of E c = 1 µV/cm, and E c to be up to 50 times lower at I c,B than at I c,E . |
