Submicron YBa2Cu3O7 xbicrystal grain boundary junctions by focused ion beam

Testa, Gianluca; Monaco, A.; Sarnelli, E.; D’Agostino, Alfred T.; Kang, Dae Joon; Tarte, E.J.; Mennema, S. H.; Bell, C. H.; Blamire, M. G.

doi:10.1088/0953-2048/17/2/009

Cited by 12 publications

(11 citation statements)

References 23 publications

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“…1 Figure 3 shows a typical I-V characteristic at T = 77 K. The critical current densities J Cj are of the order of 10 4 A/cm 2 at T = 77 K and about 2 -5 ϫ 10 5 A/cm 2 at T = 4.2 K. 17 One important feature is the complete suppression of the critical current by applying external magnetic fields ͑inset of Fig. 3͒.…”

Section: Resultsmentioning

confidence: 99%

“…A more detailed description of the fabrication procedure is reported elsewhere. 17 All the experiments have been made, with very low noise electronics, in a helium cryostat shielded by 1 thick aluminum and 3 -metal shields with a residual field lower than 1 mOe. Samples have been measured both in liquid helium ͑T = 4.2 K͒ and in liquid nitrogen ͑T =77 K͒ by using a vacuum probe covered by both a superconducting lead cylinder and a cryoperm shield.…”

Section: Methodsmentioning

confidence: 99%

“…For this analysis the use of submicron junctions 17 is very helpful for two main reasons: ͑i͒ large magnetic fields needed to modulate their critical current make a large number of vortices enter the electrodes and interact with the junction barrier, and ͑ii͒ the reduced junction size results in relatively more uniform barrier interfaces, as demonstrated in previous experiments on transport and interface properties. [18][19][20] Submicron GBJs become then a tool to study the vortex dynamics and the magnetization of superconducting thin films.…”

Section: Introductionmentioning

confidence: 99%

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Stray-field effects in submicronYBa2Cu3O7−xbicrystal grain boundary junctions

et al. 2006

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We have investigated the magnetic field dependence of the critical current in submicron YBa 2 Cu 3 O 7−x ͓001͔ tilt bicrystal grain boundary junctions. The good homogeneity of submicron grain boundary barrier interfaces, together with the large magnetic field needed to modulate the Josephson current, allow to observe several features not observed in micron size junctions, like a nonconstant modulation period, strongly dependent on the maximum applied magnetic field. Experimental results are well accounted for by a theoretical model taking into account the magnetization of the nearby electrode, and the strong interaction of its stray field with the junction interface. The analysis of the nature of this interaction and the influence of the device geometry are also relevant for potential applications of high critical temperature LSI devices.

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Section: Resultsmentioning

confidence: 99%

Section: Methodsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Stray-field effects in submicronYBa2Cu3O7−xbicrystal grain boundary junctions

et al. 2006

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“…The Au layer also prevents charging during the FIB etch and inhibits degradation of the contact area during photolithographic processes. Tracks which cross the grain boundary were patterned by standard photolithography and Ar-ion milling and then narrowed down to sub-micron dimensions using the FIB [10] to form SQUID structures [11]. Figure 1 shows the current vs voltage characteristics of a dc SQUID in the temperature range of 15 K-44 K. The Josephson current becomes almost zero at a temperature T* between 25 K and 28 K, and increases for higher temperatures.…”

Section: Hts Grain Boundary Devicesmentioning

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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“…However, once experiments involve quantitative measurements, micrometric grain boundary junctions do not guarantee reliable devices with repeatable properties. Considering the difficulties for fabricating sub-micron YBCO devices, only few experiments involving these type of junctions are available in the literature, see for instance [9,12,13]. Moreover, as far as we know, the literature is lacking of experiments testing the amplitude of the order parameter, which is a quantitative test.…”

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confidence: 99%

Influence of d-wave pairing on electrical properties of d₀-d₀submicron YBa₂Cu₃O_7−xbicrystal grain boundary junctions

Sarnelli

Adamo

Nicola

et al. 2014

J. Phys.: Conf. Ser.

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Abstract. We have fabricated submicron YBa 2 Cu 3 O 7-x grain boundary junctions using [100] tilt bicrystal substrates. In these substrates, crystal planes are tilted around the b-axis, parallel to the bicrystal line. We have obtained high-quality junctions and fitted experimental data using a recently theory accounting for d-wave symmetry of the order parameter in layered superconductors with arbitrary orientation. In our experiment, sensitive to the amplitude of the pairing state, lobes of different signs do not influence the electrical transport in the junction. Nevertheless, the effects of a non-conventional symmetry are clearly observed on the temperature dependence of the critical current.Since their discovery, an impressive number of papers dedicated to the understanding of physical mechanisms in high-critical temperature superconductors has been produced. Among these materials, intensive studies have been pursued on YBa 2 Cu 3 O 7-x (YBCO) superconductor, that has generated large curiosity in the researchers, because of its complicated phenomenology. One of the methods largely used for analyzing properties of superconductive materials is the Josephson effect [1]. The study of the Josephson effect allows the analysis of several electrical and magnetic phenomena, mirroring intrinsic properties of the junction. Typically planar technologies, used for the fabrication of tunnel junctions with conventional superconductors, generally failed. Indeed, the coherence lengths extremely short in YBCO, of the order of 2 nm in the plane and even shorter along the c-axis, forced the scientific community to look for alternative techniques for the fabrication of Josephson devices. Since then, several technologies have been introduced, as for instance junctions known as step-edge [2], rampedge [3], or grain boundary junctions [4]. The simplest and most used method was the fabrication of grain boundary junctions (GBJs) through the employment of bicrystal [4], tricrystal [5], or tetracrystal [6] substrates. This was also the fastest method for fabricating YBCO junctions and starting the analysis of electrical properties of such fascinating superconductors. Thanks to such technologies, most of exotic properties have been determined. In particular, the most important difference with respect conventional superconductors is the d-wave symmetry of the order parameter, in the form d x2-y2 [7]. This important result has been determined through phase-sensitive experiments using peculiar properties of dc-SQUIDs [5,7,8] (Superconducting Quantum Interference Devices) or rf-SQUIDs [9]. About this point, more than one convincing experiment has been carried out. However, to date, whether the symmetry of the order parameter in YBCO is fully represented by a d x2-y2 symmetry [5,10] or small components of other symmetries [11] are present, is still matter of debate. A step forward

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Submicron YBa₂Cu₃O_7 xbicrystal grain boundary junctions by focused ion beam

Cited by 12 publications

References 23 publications

Stray-field effects in submicronYBa2Cu3O7−xbicrystal grain boundary junctions

Stray-field effects in submicronYBa2Cu3O7−xbicrystal grain boundary junctions

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

Influence of d-wave pairing on electrical properties of d₀-d₀submicron YBa₂Cu₃O_7−xbicrystal grain boundary junctions

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Submicron YBa2Cu3O7 xbicrystal grain boundary junctions by focused ion beam

Cited by 12 publications

References 23 publications

Stray-field effects in submicronYBa2Cu3O7−xbicrystal grain boundary junctions

Stray-field effects in submicronYBa2Cu3O7−xbicrystal grain boundary junctions

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

Influence of d-wave pairing on electrical properties of d0-d0submicron YBa2Cu3O7−xbicrystal grain boundary junctions

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Submicron YBa₂Cu₃O_7 xbicrystal grain boundary junctions by focused ion beam

Influence of d-wave pairing on electrical properties of d₀-d₀submicron YBa₂Cu₃O_7−xbicrystal grain boundary junctions