1. a Department of Physics , Colorado School of Mines , Golden , CO 80401 , USA
2. b Department of Physics , University of Colorado , Boulder , CO 80309 , USA
3. c Department of Metallurgical and Materials Engineering Colorado , School of Mines, Golden , CO 80401 , USA
4. d Superconducting Core Technologies, Golden , CO 80401 , USA
5. e Symetrix Corporation , Colorado Springs , CO 80918 , USA