Induced change of critical current density profile in Nb/Al-AlOx/Nb Josephson junctions

11th European Conference on Applied Superconductivity

Granata, C.^1 ; Petti, L.^1 ; Rippa, M.^1 ; Rombetto, S.^1 ; Ruggiero, B.^1 ; Russo, M.^1 ; Russo, R.^1,2 ; Vettoliere, A.^1

Istituto di Cibernetica E. Caianiello Del Consiglio Nazionale Delle Ricerche, Via Campi Flegrei 34, Pozzuoli (Napoli)

80078, Italy^1

Consiglio Nazionale Delle Ricerche, Istituto per la Microelettronica e i Microsistemi, UoS di Napoli, via Pietro Castellino 111, Napoli

80131, Italy^2

关键词: Absorbance coefficients;    Josephson devices;    Junction barrier;    Localized heating;    Quantum Computing;    Spatial modulations;    Spatial resolution;    Thermal-annealing;   

Others  :  https://iopscience.iop.org/article/10.1088/1742-6596/507/4/042046/pdf
DOI  :  10.1088/1742-6596/507/4/042046

来源: IOP

【 摘 要 】

A technique to induce spatial modulation of critical current density in niobium based Josephson devices by using a selective thermal annealing is reported. By depositing a carbon film onto selected region of the Josephson element it is possible to induce a localized heating, with a spatial resolution less than 1 μm, exploiting the much higher absorbance coefficient of carbon than the niobium one. The effectiveness of such technique is demonstrated by experimental measurement of the critical current vs. magnetic field, measured at T 4.2 K, showing that the change of critical current density occurs only in the region corresponding to the absorber film area. Furthermore, the theoretical behaviour, by modelling a suitable step-like junction barrier shape, has been carried out to fit the experimental data in order to verify the selective modulation of critical current. This technique can be very useful in view of quantum computing experiments, Majorana fermions detection and superconducting magnetic sensors.