We employed scanning tunneling microscopy and spectroscopy combined with macroscopic resistivity and magnetization measurements in the study of the superconductor-to-insulator transition in ceramic Eu1.5Ce0.5NbSr2Cu2O10. This superconductor (TC = 29 K) is made insulating by hydrogen doping in a nondestructive way, allowing for a reversible transition. We found that although the samples were nominally homogeneous the resistivity and magnetization data are indicative of a granular system. Tunneling measurements directly show that the effect of hydrogen loading is to induce a random insulator-superconductor phase separation, resulting in a percolative granularlike transition.
|Original language||American English|
|Journal||Physical Review B - Condensed Matter and Materials Physics|
|State||Published - 1999|