Nanoscale SNS junction fabrication in superconductor-normal metal bilayers

Hadfield, Robert H.; Burnell, Gavin; Booij, W.E.; Lloyd, S. J.; Moseley, Richard; Blamire, M. G.

doi:10.1109/77.919546

Cited by 13 publications

(15 citation statements)

References 7 publications

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“…Furthermore, the trench depths were significantly shallower than those we have previously reported for Nb-Cu devices [11]. This is not unexpected, since the presence of the magnetic Py-Cu multilayer will strongly influence the proximity effect in the layer of Nb immediately above the multilayer.…”

Section: A Junctionssupporting

confidence: 51%

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Giant-Magnetoresistive/Superconducting Contacts and Josephson Junction Devices

Burnell

Leung

Bell

et al. 2005

IEEE Trans. Appl. Supercond.

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We have been investigating superconductor-normal metal-superconductor (SNS) (Proximity-Effect) Josephson Junctions in which the normal metal is a magnetic heterostructure in which the magnetic character can be actively controlled. As part of this program we have investigated the use of giant magnetoresistive (GMR) Cu-Py multilayers as the barrier in variable thickness planar bridge SNS junctions in addition to in-plane S-GMR contacts. In this paper we report on the latest results from our devices which have been fabricated using our established focussed ion beam (FIB) processes.

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Section: A Junctionssupporting

confidence: 51%

“…The variable thickness bridges were fabricated using our now well established FIB technique [10], [11]. Briefly, micrometer-scale tracks and contact pads were defined using conventional photolithography and broad beam ion milling in a film consisting of a Cu-Py multilayer and 120 nm Nb deposited as described above.…”

Section: B Junction Fabricationmentioning

confidence: 99%

Giant-Magnetoresistive/Superconducting Contacts and Josephson Junction Devices

Burnell

Leung

Bell

et al. 2005

IEEE Trans. Appl. Supercond.

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“…The resulting nano-constrictions behave as overdamped, or slighty hysteretic, SNS-like planar Josephson junctions, whose width is defined by the strip geometry, while the two other dimensions are defined by the FIB milling process. Our fabrication process is similar to that reported in [13], [14], but does not require a normal layer below the Nb superconducting film acting as a metal barrier and heat sink. To further improve the quality of the junctions, the Nb surface has been anodized to reduce the damaging effect induced by ion implantation [23], which modifies the superconducting properties of the exposed Nb film.…”

Section: Introductionmentioning

confidence: 96%

Thickness Modulated Niobium Nanoconstrictions by Focused Ion Beam and Anodization

Leo

Fretto

Lacquaniti

et al. 2016

IEEE Trans. Appl. Supercond.

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We have fabricated microstrips of Nb thin films by DC magnetron sputtering and lif-off. Focused ion beam (FIB) has been used to mill the surface of the films in a nanometer-sized region across the width of the strip. FIB has the side effect of implanting Ga + ions on the exposed surface of Nb, damaging the film and modifying its superconducting properties. To overcome this problem, the surface of the FIB-milled Nb films has been passivated by anodization, including the damaged region of the strip into the oxidized layer. Anodization also allows to finely tune the thickness of the nano-constrictions after the milling process. We report here the effect of FIB exposure and anodization voltage on the superconducting transition temperature and on the temperature dependence of the resistance of the Nb nanoconstrictions. We also show some preliminary results suggesting that these devices behave as overdamped SNS-like Josephson junctions.

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“…2) [16]. The results of this study led us to propose a model whereby Josephson current flows in parallel through two interacting channels: the SS'S channel through the damaged and proximitised Nb at the bottom of the trench and the SNS channel through the Cu beneath (S' = superconductor above its T C ) [17]. The optimum properties were achieved with a thick (~100 nm), clean Cu layer.…”

Section: Planar Sns Junction Fabrication and Characterisationmentioning

confidence: 96%

“…If a microwave signal is applied to a series array of N phase-locked Josephson junctions, the first Shapiro step will appear at a voltage V = N(h/2e)f , where f is the microwave frequency and h and e are Planck's constant and the electronic charge respectively; an example of phase locking in a 10-junction array is also shown in Fig. 3 [17]. The advantage of this technology is the high packing density per unit length of track with which junctions can be positioned.…”

Section: Sns Junction Arrays and Circular Junctionsmentioning

confidence: 99%

Focused ion beam fabrication and properties of nanoscale Josephson junctions for sensors and other applications

Blamire

Bell

Burnell

et al. 2005

phys. stat. sol. (c)

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PACS 74.50.+r, 74.81.Fa, 85.25.Cp, The methods of superconducting device fabrication by lithography and multilevel processing usually require a number of processing steps with lithographic resolution and alignment adequate for the scale of the device be fabricated. As an alternative, the focused ion beam (FIB) microscope is increasingly being used directly to fabricate devices. A major advantage of using a FIB compared to other lithography methods is its flexibility and high resolution. It allows in-situ, milling (~5 nm at a beam current of 1 pA) to a variety of depths, and imaging (2 nm) of the sample. In this paper we describe our development of junction fabrication techniques using the FIB and their application in creating a range of potential sensor devices and quantum electronics applications.1 Introduction Focused ion beam (FIB) systems offer the ease of use of a scanning electron microscope (SEM) but with sectioning and cross-sectional imaging capabilities which SEMs lack. Historically, their development was driven by the semiconductor production industry but their increasing availability within research institutions has enabled the development of new applications making widespread the use and development of these techniques.In a typical FIB system a focused ion-beam ejected from a liquid metal ion source (usually Ga), with a spot size of less than 10 nm, is scanned across a sample in a manner analogous to a SEM. Imaging using secondary electrons provides surface information with similar resolution to that obtainable from an SEM; however the main applications arise from the use of ions as the scanned species. These include compositional imaging via secondary ions, direct etching of material in selected regions for in-situ sectioning and imaging, microfabrication, transmission electron microscopy specimen preparation, and localised deposition and implantation of metal and insulator structures. The unique combination of 10 nm resolution imaging with the ability both to remove and to deposit material in selected areas provides a means of performing experiments which would otherwise be impossible or unreasonably timeconsuming.At its most general, a Josephson junction consists of two superconducting electrodes separated by a weak-link in which superconductivity is eliminated or suppressed: for example by an insulating tunnel barrier in a superconductor -insulator -superconductor (SIS) junction or by a thin non-superconducting metal layer in a superconductor -normal -superconductor (SNS) junction. All Josephson junctions for

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Nanoscale SNS junction fabrication in superconductor-normal metal bilayers

Cited by 13 publications

References 7 publications

Giant-Magnetoresistive/Superconducting Contacts and Josephson Junction Devices

Giant-Magnetoresistive/Superconducting Contacts and Josephson Junction Devices

Thickness Modulated Niobium Nanoconstrictions by Focused Ion Beam and Anodization

Focused ion beam fabrication and properties of nanoscale Josephson junctions for sensors and other applications

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