Long-time stable high-temperature superconducting DC-SQUID gradiometers with silicon dioxide passivation for measurements with superconducting flux transformers

Seidel, P.; Becker, Christoph; Steppke, Alexander; Buettner, M; Schneidewind, H.; Große, Veit; Zieger, Gabriel; Schmidl, F.

doi:10.1088/0953-2048/20/11/s15

Cited by 9 publications

(6 citation statements)

References 14 publications

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“…A similar technique has been presented for vortex pinning in YBCO thin films by Mikheenko et al 7. It allows to control the particle size over a range of a few nanometers to one micron and can be utilized to lower the contact resistance to bonding wires 8, 9, which often is the source of current noise. The aim of this work is to analyze particle formation and size distribution as well as crystallographic properties of the particles and the circumjacent YBCO film.…”

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confidence: 99%

Formation of gold nano‐particles during pulsed laser deposition of YBa₂Cu₃O_7–δ thin films

Große¹,

Engmann

Schmidl

et al. 2010

Physica Rapid Research Ltrs

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The mobility of flux vortices in high temperature superconductors in general, and YBa 2 Cu 3 O 7-δ (YBCO) thin films in particular, is an essential limiting factor determining the performance of superconducting devices, such as Josephson junctions and magnetic field sensors. Flux noise properties and critical current density can be improved by adding artificial defects serving as pinning centers. A simple and effective technique to obtain such defects is decorating the substrate with prefabricated nano-particles before YBCO film deposition. A number of materials, such as CeO 2 [1], Y 2 O 3 [2, 3] as well as MgO, BaZrO 3 and Ir [4][5][6], have successfully been tested in this regard.In this work we utilized the tendency of thin gold (Au) layers to self-assemble nano-scale particles at elevated temperatures during deposition of the YBCO film. A similar technique has been presented for vortex pinning in YBCO thin films by Mikheenko et al. [7]. It allows to control the particle size over a range of a few nanometers to one micron and can be utilized to lower the contact resistance to bonding wires [8,9], which often is the source of current noise. The aim of this work is to analyze particle formation and size distribution as well as crystallographic properties of the particles and the circumjacent YBCO film.Prior to the growth of the YBCO films a thin gold layer was deposited on SrTiO 3 (STO) single crystal substrates under high vacuum conditions (p 0 < 5 × 10 -4 Pa). For layer thicknesses up to 20 nm this was accomplished by pulsed laser deposition using a KrF excimer laser (λ = 248 nm) at a repetition rate of 10 Hz and a laser fluence of 1.3 J/cm 2 at the target. Under these conditions the growth rate was 4.4 nm/min. Thicker Au layers were grown by dc-sputtering to limit the deposition time.Subsequently, the substrate was heated to 750 °C. Again using the KrF excimer laser a 150 nm thick YBCO film was then grown in an atmosphere of pure oxygen 2 O ( p = 50 Pa). The repetition rate was set to 5 Hz and the laser fluence to 2.2 J/cm 2 . After deposition the film was slowly cooled to room temperature at a rate of 50 K/min in an oxygen atmosphere of 2 O p = 8 × 10 4 Pa. During film growth small particles evolve from the Au layer.Transmission electron microscopic (TEM) images show that particles having diameters much smaller than the YBCO film thickness preferentially grow at the YBCO In order to improve transport and noise properties of YBa 2 Cu 3 O 7-δ thin films, we studied a technique to produce gold nano-particles in these films. We report on the formation of these particles from thin gold layers during pulsed laser deposition of YBa 2 Cu 3 O 7-δ . Depending on initial gold layer thickness we analyzed their size distribution and structural properties. Gold particles preferentially grow at the YBa 2 Cu 3 O 7-δ surface and the SrTiO 3 /YBa 2 Cu 3 O 7-δ interface and show an epitaxial alignment parallel to the YBCO 001 direction. We discuss the influence of these particles on the crystal structure of YBa 2 Cu 3 O 7-δ in...

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confidence: 99%

Formation of gold nano‐particles during pulsed laser deposition of YBa₂Cu₃O_7–δ thin films

Große¹,

Engmann

Schmidl

et al. 2010

Physica Rapid Research Ltrs

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“…In particular, the incorporation of highly efficient pinning centres to enhance the critical current density [1,2] and the development of new growth processes enabling very high growth rates [3] has made YBCO the superconducting material of choice for the preparation of coated conductors [4]. Furthermore, using YBCO thin films, magnetic sensor devices working at the boiling point of liquid nitrogen can be realized [5][6][7]. However, YBCO unfortunately is extremely sensitive to its environment as it decomposes in the presence of water [8] or CO 2 [9].…”

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confidence: 99%

Structural properties of gold modified YBa₂Cu₃O_7−δthin films

Katzer

Westerhausen

Uschmann

et al. 2013

Supercond. Sci. Technol.

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YBa 2 Cu 3 O 7−δ thin films were prepared by pulsed laser deposition whereby single-crystalline Au nanoparticles were embedded via a self-assembly process out of an initial Au seed layer. The size of the Au nanoparticles was controlled via the initial Au seed layer thickness. During the growth of the YBa 2 Cu 3 O 7−δ matrix the nanoparticles are partly lifted on top of the YBa 2 Cu 3 O 7−δ thin film. The inclusion of nanoparticles thus offers the possibility of shunting thin contamination layers on top of the YBa 2 Cu 3 O 7−δ thin film and even allows contact with the lower electrode in multilayer systems without using difficult etching methods. Using x-ray diffraction and scanning electron microscopy we show that the growth conditions of the YBa 2 Cu 3 O 7−δ matrix are modified, resulting in less a-axis growth and an enhanced oxygen stoichiometry.

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“…Here h is Planck's constant and e is the elementary charge. SQUIDs are the most sensitive magnetic field detectors used for a large variety of applications ranging from non destructive evaluation (NDE) (Carr et al, 2003) to low field magnetic resonance imaging (MRI) (Schlenga et al, 1999) to magnetic nanoparticles detections (Seidel et al, 2007). They are considered the most successful application of the Josephson effect and the many text books and reviews that have been written through the years provide an in-depth systematic treatment of the fundamental science, fabrication, and operation of dc SQUIDs and their many applications.…”

Section: Introductionmentioning

confidence: 99%

d-Wave YBCO dc superconductive quantum interference devices (dc SQUIDs)

Lombardi

2011

High-Temperature Superconductors

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Long-time stable high-temperature superconducting DC-SQUID gradiometers with silicon dioxide passivation for measurements with superconducting flux transformers

Cited by 9 publications

References 14 publications

Formation of gold nano‐particles during pulsed laser deposition of YBa₂Cu₃O_7–δ thin films

Formation of gold nano‐particles during pulsed laser deposition of YBa₂Cu₃O_7–δ thin films

Structural properties of gold modified YBa₂Cu₃O_7−δthin films

d-Wave YBCO dc superconductive quantum interference devices (dc SQUIDs)

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Long-time stable high-temperature superconducting DC-SQUID gradiometers with silicon dioxide passivation for measurements with superconducting flux transformers

Cited by 9 publications

References 14 publications

Formation of gold nano‐particles during pulsed laser deposition of YBa2Cu3O7–δ thin films

Formation of gold nano‐particles during pulsed laser deposition of YBa2Cu3O7–δ thin films

Structural properties of gold modified YBa2Cu3O7−δthin films

d-Wave YBCO dc superconductive quantum interference devices (dc SQUIDs)

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Formation of gold nano‐particles during pulsed laser deposition of YBa₂Cu₃O_7–δ thin films

Formation of gold nano‐particles during pulsed laser deposition of YBa₂Cu₃O_7–δ thin films

Structural properties of gold modified YBa₂Cu₃O_7−δthin films