Polycrystalline NbRe superconducting films deposited by direct current magnetron sputtering

Cirillo, C.; Caputo, M.; Divitini, G.; Robinson, Jason W. A.; Attanasio, C.

doi:10.1016/j.tsf.2022.139450

Cited by 9 publications

(9 citation statements)

References 29 publications

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“…The RRR is defined as the ratio of the resistivity at room temperature and at 10 K, that is, RRR = ρ 300K /ρ 10K = R 300K / R 10K . The values of T c are not significantly smaller than the values measured on unpatterned films of the same thickness [ 4 , 8 ]. The rounding present at the onset of both the curves is due to the paraconductivity phenomenon, whose nature has been analyzed in detail in the case of unstructured NbReN films of different thickness [ 4 ].…”

Section: Resultsmentioning

confidence: 87%

“…In order to confirm these results, we are currently working on different experiments that may give more direct access to the order parameter in these systems. Regarding the aforementioned purpose, while in the case of NbRe it is now even more evident that films with larger crystallites are mandatory [ 7 – 8 12 ], detailed analyses of the NbReN crystal structure are still lacking and need to be performed.…”

Section: Resultsmentioning

confidence: 99%

“…The NbReN films were structured by using direct laser writer exposure followed by argon ion etching into constriction-type bridges with w = 2 μm and L = 700 μm. Further details on the fabrication procedure of the films are reported elsewhere [ 4 , 8 ].…”

Section: Methodsmentioning

confidence: 99%

“…Apart from the reduced values of the superconducting gap and short quasi-particle relaxation times [ 5 ], the property that makes these materials appropriate to be used as SNSPDs is the high value of the electrical resistivity [ 6 ]. This feature is related to the polycrystalline or amorphous nature of these materials when deposited in a thin-film form [ 4 , 7 – 8 ]. In addition to the applicative interest, the study of these materials is relevant from a fundamental point of view.…”

Section: Introductionmentioning

confidence: 99%

“…This non-centrosymmetric nature of the material leads to intriguing and unconventional physical properties such as the time-reversal symmetry breaking observed with muon-spin rotation and relaxation studies [ 13 ] and large values of the upper critical magnetic fields [ 11 , 14 ], which are above the Pauli paramagnetic limit [ 15 – 16 ]. In the case of thin films, the structure of NbRe is polycrystalline with grains of small dimensions, typically of the order of 2–3 nm [ 7 – 8 17 ]. NbReN films also present a polycrystalline nature with a moderate texture.…”

Section: Introductionmentioning

confidence: 99%

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Upper critical magnetic field in NbRe and NbReN micrometric strips

Kakhaki¹,

Leo²,

Chianese³

et al. 2023

Beilstein J. Nanotechnol.

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Non-centrosymmetric superconductors have recently received significant interest due to their intriguing physical properties such as multigap and nodal superconductivity, helical vortex states, as well as non-trivial topological effects. Moreover, large values of the upper critical magnetic field have been reported in these materials. Here, we focus on the study of the temperature dependence of the perpendicular magnetic field of NbRe and NbReN films patterned in micrometric strips. The experimental data are studied within the Werthamer–Helfand–Hohenberg theory, which considers both orbital and Zeeman pair breaking. The analysis of the results shows different behavior for the two materials with a Pauli contribution relevant only in the case of NbReN.

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Section: Resultsmentioning

confidence: 87%

Section: Resultsmentioning

confidence: 99%

Section: Methodsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 3 more Smart Citations

Upper critical magnetic field in NbRe and NbReN micrometric strips

Kakhaki¹,

Leo²,

Chianese³

et al. 2023

Beilstein J. Nanotechnol.

Self Cite

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Gate-controlled supercurrent effect in dry-etched Dayem bridges of non-centrosymmetric niobium rhenium

Koch,

Cirillo,

Battisti

et al. 2024

Nano Res.

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The application of a gate voltage to control the superconducting current flowing through a nanoscale superconducting constriction, named as gate-controlled supercurrent (GCS), has raised great interest for fundamental and technological reasons. To gain a deeper understanding of this effect and develop superconducting technologies based on it, the material and physical parameters crucial for the GCS effect must be identified. Top-down fabrication protocols should also be optimized to increase device scalability, although studies suggest that top-down fabricated devices are more resilient to show a GCS. Here, we investigate gated superconducting nanobridges made with a top-down fabrication process from thin films of the non-centrosymmetric superconductor niobium rhenium with varying ratios of the constituents (NbRe). Unlike other devices previously reported and made with a top-down approach, our NbRe devices systematically exhibit a GCS effect when they were fabricated from NbRe thin films with small grain size and etched in specific conditions. These observations pave the way for the realization of top-down-made GCS devices with high scalability. Our results also imply that physical parameters like structural disorder and surface physical properties of the nanobridges, which can be in turn modified by the fabrication process, are crucial for a GCS observation, providing therefore also important insights into the physics underlying the GCS effect.

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