Direct-writing of complex 3D nano-superconductors*

Innovative schemes have taken advantage of the third dimension (3D) for the development of advanced electronic components. Thus, 3D nano-superconductors could be implemented in the next generation of energy efficient electronic devices. Here, we introduce a template-free nano-lithography method to fabricate in a single-step 3D nano-superconductors with arbitrary geometry. They become superconducting at 7 K and show large critical magnetic field and critical current density. Particularly, we have prepared 3D superconducting WC hollow nanowires by decomposing tungsten hexacarbonyl molecules with a highly-focused He⁺ ion beam, with outer diameters down to 32 nm and inner ones down to 6 nm [1, 2]. In addition, we have grown nanohelices with on-demand geometries, with dimensions down to 100 nm in diameter, and aspect ratio up to 65. Given its helical 3D geometry, fingerprints of vortex and phase-slip patterns are experimentally identified and supported by numerical simulations based on the time-dependent Ginzburg-Landau equation [3].

[1] R. Córdoba et al., Nano Lett. 2018, 18, 2, 1379–1386.
[2] R. Córdoba et al., Beilstein J. Nanotechnol. 2020, 11, 1198–1206.
[3] R. Córdoba et al., Nano Lett. 2019, 19, 12, 8597–8604.