Superconducting Properties and Electron Scattering Mechanisms in a Nb Film with a Single Weak-Link Excavated by Focused Ion Beam

Materials

卷:14

Davi Araujo Dalbuquerque Chaves¹  Marlon Ivan Valerio-Cuadros¹  Maycon Motta¹  Wilson Aires Ortiz¹  Fabiano Colauto¹  Tom Henning Johansen²  Ana Augusta Mendonça de Oliveira³  Antônio Marcos Helgueira de Andrade⁴ 

[1] Departamento de Física, Universidade Federal de São Carlos, São Carlos 13565-905, SP, Brazil;

[2] Department of Physics, University of Oslo, POB 1048, Blindern, NO-0316 Oslo, Norway;

[3] Instituto Federal de Educação, Ciência e Tecnologia de São Paulo, Campus São Carlos, São Carlos 13565-905, SP, Brazil;

[4] Instituto de Física, Universidade Federal do Rio Grande do Sul, Porto Alegre 91501-970, RS, Brazil;

关键词: granular superconductivity;    weak-link;    thin film;    ion implantation;   

DOI  :  10.3390/ma14237274

来源: DOAJ

【 摘 要 】

Granularity is one of the main features restricting the maximum current which a superconductor can carry without losses, persisting as an important research topic when applications are concerned. To directly observe its effects on a typical thin superconducting specimen, we have modeled the simplest possible granular system by fabricating a single artificial weak-link in the center of a high-quality Nb film using the focused ion beam technique. Then, its microstructural, magnetic, and electric properties in both normal and superconducting states were studied. AC susceptibility, DC magnetization, and magneto-transport measurements reveal well-known granularity signatures and how they negatively affect superconductivity. Moreover, we also investigate the normal state electron scattering mechanisms in the Boltzmann theory framework. The results clearly demonstrate the effect of the milling technique, giving rise to an additional quadratic-in-temperature contribution to the usual cubic-in-temperature sd band scattering for the Nb film. Finally, by analyzing samples with varying density of incorporated defects, the emergence of the additional contribution is correlated to a decrease in their critical temperature, in agreement with recent theoretical results.

【 授权许可】

Unknown