He+ focused ion beam for fabricating vertical superconducting crystalline hollow nanowires

Significance 

Superconducting materials are widely used in applications for energy generators and storage due to their capability of transporting electricity without energy losses. However, their required performance for those applications is normally achieved by using nanostructuring. When the sizes of the superconductors are scaled down to the nanoscale in the range of their superconducting coherence length the novel physical properties emerge. To the end, the use of nano superconductivity is extended to quantum computing and nanoelectronics. The available nanoscale approaches are capable of fabricating quasi-1-dimensional superconducting nanowires that preserve a dissipation-free energy state.

However, the difficulty of fabricating 3D superconducting nano-objects still represents a challenge and only a few examples of 3D nanosuperconductors have been reported in literature.

A group of researchers at the Material Science Institute of Aragon (ICMA), from the Council of Research of Spain (CSIC) and the University of de Zaragoza, Dr. Rosa Córdoba, Dr. Alfonso Ibarra and Professor José Mª De Teresa, in collaboration with Dr. Dominique Mailly from CNRS developed a novel methodology for fabricating 3D superconducting crystalline WC hollow nanowires with diameters down to 32 nm and aspect ratio above 200. The methodology was based on using highly- focused Heion-beam in spot mode to decompose a W(CO)precursor. The growth of the WC pillar occurs around the ion beam spot, mainly due to the interaction of secondary electrons with the adsorbed precursor molecules, while it forms a cavity at the center of the pillar due to the simultaneous Hebeam milling.

The high resolution achieved for the growth of the nanowires was attributed to the use of a small 0.3 nm He+ beam spot. The large grains sizes and structure displayed also conformed well with the WC1-x face-centered cubic (FCC) phase.

Such nanowires become superconductors at 6.4 K and also exhibit large critical magnetic fields and current densities. Consequently, their superconducting properties were improved compared to those obtained in the nanowires grown by the Ga+ FIB method, as done so far.

The study by Professor José M De Teresa and his research team is the first to successfully develop a novel methodology for fabricating 3D superconducting crystalline WC hollow nanowires and will, therefore, pave the way for the development of 3D nano superconductors. Furthermore, the robust superconducting properties shown by these nanowires are excellent for broad applications in various fields such as quantum computing and nanoelectronics.

 

He focused ion beam for fabricating vertical superconducting crystalline hollow nanowires. Advances in Engineering

 

About the author

Prof. José María De Teresa leads the group of Nanofabrication and Advanced Microscopies at the Institute of Materials Science of Aragon (CSIC-University of Zaragoza, Spain). He is the coordinator of the Spanish network on Nanolithography (NANOLITO) and the FIB-SEM area in the Spanish National facility for Advanced Microscopies. Board member of the Condensed Matter Division in the European Physical Society.

His main research interests are nanofabrication with focused electron and ion beams, magnetic nanostructures, nano-superconductivity and epitaxial graphene. He has published more than 200 research articles (h factor=40) and has given 75 invited conferences. He has supervised 12 PhD thesis, 19 Master thesis and led 32 research projects.

He is co-founder of the spin-off company Graphene and Nanotechnologies and co-author of 6 patents, one of them under exploitation. From 1998 to 2000 he developed an individual Marie Curie project under the supervision of the Nobel Prize winner Albert Fert in CNRS-Thomson (Paris).

About the author

Rosa Córdoba is presently a Postdoctoral researcher at the Universidad Autónoma de Madrid/Instituto de Ciencia de Materiales de Aragón, ICMA (Universidad de Zaragoza-CSIC). She is strongly interacting with the group “Nanofabrication of functional materials and devices (NANOFAB)” led by Prof.  J.M. De Teresa at ICMA (CSIC-University of Zaragoza).

With a background in Material Science, her research interests focus on the nanofabrication of advanced materials in the three dimensions of space by using focused beams of electrons or ions (Ga+, Ne+ and He+). She has carried out novel studies on the composition and microstructure of the nanostructures at the nanoscale, as well as on their magnetotransport properties. Such advanced nanomaterials could be used as a building blocks for a future generation of nano-electronic devices.

She is co‐author of 47 publications in research journals and 7 book chapters and, its total number of citations is 941. Her H‐index is 18. She has participated in 47 national or international conferences/workshops, in which she has given 20 oral communications, 6 of them were invited oral contributions.

Reference

Córdoba, R., Ibarra, A., Mailly, D., & De Teresa, J. M (2018). Vertical Growth of Superconducting Crystalline Hollow Nanowires by He+ Focused Ion Beam Induced Deposition. Nano Letters, 18(2), 1379-1386. 95, 568-576

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