Heating and flux flow in niobium variable-thickness bridges

Publisher Website
Google Scholar
Abstract
The properties of niobium superconducting microbridges consisting of a thin‐film bridge 300 Å thick, 1 μm wide, and 0.5 μm long joining two bulk films 5000 Å thick have been studied by measurements of I‐V and dV/dI versus V as functions of temperature and microwave power and by microwave mixing experiments. Near Tc these bridges behave as nearly ideal Josephson junctions but at lower temperature their characteristics appear to be determined by flux flow. Hysteresis of the I‐V curves, depression of the energy gap, a feature interpreted as the onset of a self‐sustaining hot spot, and bolometric mixing can all be described very well by a simple heating model.