Nano-Nb Superconducting 3D Josephson Junctions Arrays in Cu-Normal Matrix: Superconducting Phase Coherence and Quantum Fluctuations Properties

Abstract

To address the complex interplay of microstructural evolution, phase separation, superconductivity coherence and quantum fluctuations, we prepared Cuxwt%Nb series of granular samples by rapidly cooling, where the niobium concentration varied (x = 3, 5, 15, 20). By employing this method, we successfully obtained samples characterized by well-defined precipitates of niobium, featuring regular sizes and grain spacing. The goal was to establish a systematic and robust method approach for obtaining samples with different of sub-micrometric precipitates distributions but also to investigate their superconducting properties. Structural characterization by optical and Scanning Electron Microscopy, dc Mdc[H,T] ac inductive , as well the magneto-transport measures rhodc[H,T], Rdc[V,I.H,T], I[V,H,T] and [H,T,I] were done. Also, using a micro Hall sensor with 10 measuring transverse voltage bridges regularly distributed, we were able to obtain the real external applied magnetic field value inside of the chamber sample space. Thus e studied the dependence of configuration of the Nb grains in the superconducting coupling order parameter properties that connects the grains superconductors to the normal Cu matrix. We verify through magnetization and transport measures the signature of the double transition. This, when we apply current of different intensities, in the transport measures, and different field values, in the inductive measures. This behavior is an indication that our system is made up of by a collection of superconducting grains immersed in a well-organized in a non-superconducting matrix. The results indicate that the superconducting properties of these systems are manifested usually through two transition temperatures Tc(H) e TcJ(H).