Anomalous negative resistance in superconducting vanadium nanowires

Low-temperature electrical transport measurements were performed on large arrays of 150-nm-wide superconducting vanadium (V) wires covered with either a thin layer of Au (V/Au) or Fe (V/Fe). The measurements were conducted using various electrical contact geometries. Our results show that a particular arrangement of the electrical contacts in combination with the superconducting proximity effect can result in a pronounced ``negative resistance'' anomaly below the resistive transition. We demonstrate that this ``negative resistance'' can be clearly reproduced by constructing resistor circuits based upon the particular contact arrangement.