(a) View of the cryogenic microscope head suspended on a 10 cm-high copper frame: (i) piezoelectric scanner tubes, (ii) AFM/STM probe, (iii) sample holder, (iv) micro-coax filters, (v) Attocube piezo-electric positioners, and (vi) mechanical isolation springs. (b) Zoom-in picture on the AFM/STM probe showing the tungsten tip glued by silver epoxy on a quartz tuning fork, here without its shielding box. (c) Schematic of the circuit connecting the SNS sample, enabling to simultaneously perform I(V) transport experiments and local tunnel spectroscopies I T (V T ).
Operation of the coarse positioning system at a bath temperature of 90 mK. (a) AFM topographical image of a tracking symbol. (b) Superposed images after a move in − Y and + Y directions, with 8 pulses of 45 V amplitude. (c) Superposed images after − X and + X movements, with 3 pulses of 45 V amplitude. (d) Temperature evolution of the refrigerator cold plate due to a X, Y, or Z piezo-electric positioners displacement of 10 steps at a 45 V bias amplitude.
Scanning electron microscopy image showing the pattern of different symbols used to localize by AFM the sample at low temperature. Added on top of this image, the AFM pictures and associated numbers represent the different steps of a typical localization procedure performed at 90 mK. On the left: zoom on one of the low resolution image recorded during this procedure.
Typical measurements obtained with our cryogenic AFM/STM on a hybrid Josephson junction at 90 mK. (a) AFM image of the Al/Cu/Al junction. The cross indicates where spectroscopies in out-of-equilibrium conditions were realized, see Fig. 5(b). (b) Color plot of local spectroscopic data dI T /dV T (V T ) performed every 100 nm along the dotted arrow with a tunnel resistance of 10 .
Typical measurements obtained with our cryogenic AFM/STM on a hybrid Josephson junction at 90 mK. (a) and (b) current-voltage characteristics I(V) of the junction measured as described in Fig. 1(c) and over two different bias current ranges. Some hysteresis is observed. (c) Local spectroscopic data dI T /dV T (V T ) measured on one aluminum lead, see Fig. 4, while current-biasing the sample close to the local critical current of the lead.
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