Creating nanostructured superconductors on demand by local current annealing

Abstract

Abstract:Superconductivity results from a Bose condensate of Cooper-paired electrons with a macroscopic quantum wavefunction. Dramatic effects can occur when the region of the condensate is shaped and confined to the nanometer scale. Recent progress in nanostructured superconductors has revealed a route to topological superconductivity, with possible applications in quantum computing. However, challenges remain in controlling the shape and size of specific superconducting materials. Here, we report a new method to create nanostructured superconductors by partial crystallization of the half-Heusler material, YPtBi. Superconducting islands, with diameters in the range of 100 nm, were reproducibly created by local current annealing of disordered YPtBi in the tunneling junction of a scanning tunneling microscope (STM). We characterize the superconducting island properties by scanning tunneling spectroscopic measurements to determine the gap energy, critical temperature and field, coherence length, and vortex formations. These results show unique properties of a confined superconductor and demonstrate that this new method holds promise to create tailored superconductors for a wide variety of nanometer scale applications.

Campbell penetration depth in low carrier density superconductor YPtBi

“…Perhaps it is related to the third critical field in superconductors predicted theoretically by Saint-James and Gennes [43] when a thin superconducting layer is formed on the flat surface parallel to the field. Recently, a surface-sensitive tunneling experiment on YPtBi detected energy gap spectra at higher temperatures than T c ≈ 0.8 K [44]. A similar signature of the superconducting phase was reported in another half-Heusler compound LuPtBi, which was attributed to the presence of Van Hove singularity near E F [45] and surface pairing states [46].…”

Strain engineering a 4a×√3a charge-density-wave phase in transition-metal dichalcogenide 1T−VSe2Zhang1, Ha2, Baek3 et al. 2017Phys. Rev. MaterialsSelf Cite513340View full textAdd to dashboardCite

“…Sample temperatures almost coincide with the dilution refrigerator temperatures down to 150 mK. At lower temperatures, the sample temperatures remain at (150±15) mK due to RF heating determined from fitting of superconducting Al spectra [53,62]. The STM system contains facilities for MBE growth of samples and probe tip preparation.…”

“…In analogy with broadened superconducting spectra, a more direct measure of the gap are the inflection points inside of the gap, rather than the positions of the broadened coherence peaks. The latter shift to higher energies and thus overestimates the energy gap, as seen, for example, in temperature broadened spectra [62]. We consequently use the inflection points of the “V” shaped gap, determined by minima and maxima in the derivative of the differential conductance spectra, to systematically determine the CDW 2Δ gap, as shown in Figs.…”

Achieving μeV tunneling resolution in an in-operando scanning tunneling microscopy, atomic force microscopy, and magnetotransport system for quantum materials research

“…[6][7][8][9][10][11][12][13][14][15][16][17][18][19][20] Although SPM instruments have been developed that operate at temperatures down to ≈ 10 mK, none of them have achieved a tunneling energy resolution equivalent to their operating temperature. More typically, instruments show a noise-induced operating resolution equivalent to 150 mK-200 mK, 10,12,17,20,21 even though the instrument is operating at temperatures of almost ten times lower, although some progress has been made recently demonstrating tunneling resolutions below 100 mK. 13,19 In contrast, magnetotransport instruments deliver measurements with resolutions close to their base temperatures of (10 mK-20 mK).…”