Thomas QUAGLIO's Thesis Defense : "Local spectroscopies on hybrid superconducting nanostructures out of equilibrium"

Thursday 19 January 2012 at 2pm

Room Remy Lemaire - K223
Building K - Institut Néel
25 rue des martyrs - 3800 Grenoble

Thomas QUAGLIO (Institut Néel)  

Thesis supervisor: Hervé COURTOIS

This work is focused on the study of a mesoscopic nanocircuit using a microscope combining atomic force microscopy (AFM) and scanning tunneling microscopy (STM) at very low temperature (~100 mK). To perform AFM measurements, we use quartz tunning forks covered with metallic electrodes on which we glue the tip. By vibrating the tunning fork, we can localize the sample using AFM. Then, switching off the vibration, we can perform local spectroscopies along the conductive part. This work is focused on hybrid Josephson junctions composed of a normal metal (copper) island of approximately 1 µm separating two superconductors (aluminium). The current-voltage characteristics of these junctions become hysteretic at very low temperature because of thermal dissipation in the normal part. We achieved the localization of a unique sample and performed simultaneously transport measurements and local spectroscopies. This defence will present the results obtained on this type of junction, in particular, the termal dissipation in such samples.