Diploma work: Methods for electronic transport characterization of superconducting junctions

by Johan Blockmar (Stockholm University, Department of Physics)

Monday 20 Oct 2008, 10:00 → 12:00 Europe/Stockholm

A2:1041

A technique for the simultaneous direct measurement of current-voltage (I-V) and dI/dV is developed and tested. A slowly oscillating signal is used to trace out the main I-V characteristic while a higher frequency ripple is applied for lock-in measurements of the curve slope dI/dV. Software for waveform generation, system communication and data discrimination is developed. Experiments show that direct measurement of dI/dV gives slightly better resolution compared to the derivative being calculated from I-V data. The direct measurement also has the advantage of being in real time. The technique is applied to study the dI/dV of intrinsic Josephson junctions, looking for signs of Fiske steps and phonon resonances.