Nanostructured superconductive sensors based on quantum interference effect for high sensitive nanoscale applications

Recently it has been proven that the magnetic response of magnetic nano-objects such as nanoparticles, nanobeads, and small cluster of molecules can be effectively measured by using a Superconducting Quantum Interference Device (SQUID) with a small sensitive area. Here, we present a high sensitivity nanoSQUID based on deep submicrometer Josephson tunnel junctions fabricated by a Focused Ion Beam (FIB) sculpting method. The nanosensor consists of a niobium superconducting loop (0.4 × 1.0 μm2) interrupted by two sandwich nanojunctions (Nb/Al-AlOx/Nb) having an area of about (300 × 300) nm2. An experimental investigation of the main characteristics of such nanodevice as a function of the temperature is presented