Dynamic properties of high-Tc superconducting nano-junctions made with a focused helium ion beam

摘要

( ) Image of a JJ using the imaging mode of the He-FIB microscope. The light grey area in between dashed lines is the superconducting channel defined by HEII The horizontal line is the 600 ionsm dose irradiated zone, which corresponds to the barrier of the JJ. ( ) Sketch of the circuit used to measure the detector response signal . A RF signal whose amplitude is modulated at the frequency is sent onto the JJ via an antenna. is measured with a lock-in amplifier at . The JJ is described according to the RSJ model, as a junction in parallel with a resistance . ( ) vs curves (solid lines) for JJ made using different irradiation doses: 200 ionsm (blue), 400 ionsm (green) and 600 ionsm (red). Same color code for panels ( ). Below , (symbols) is extracted from RSJ fits. Dashed lines show the linear decrease of ( ) curves below . ( ) vs for different irradiation doses. Dashed lines are quadratic fits. :  −  characteristics of a 200 ionsm JJ. Blue line are data and black line is the RSJ fit. ( ) product vs for different irradiation doses. Colored areas are calculated from the dashed lines in ( , ), and correspond to the Josephson regimes.