Comparison of Au-free versus Au-doped YBa2Cu3O7−δ single crystals

Claus, H.; Yang, Stephen J. H.; Viswanathan, H. K.; Crabtree, G. W.; Downey, J.W.; Veal, B. W.

doi:10.1016/0921-4534(93)90775-l

Cited by 15 publications

(3 citation statements)

References 12 publications

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“…In a study on a high quality Au-free Y123 single crystal, Claus et al 13,14 demonstrated that overdoping, as manifested by a maximum in T c versus the oxygen concentration, exists in Au-doped crystals but to a smaller extent than in Au-free crystals. They proposed that this difference should be due to a decreased oxygen solubility in the Au-doped crystals.…”

Section: Resultsmentioning

confidence: 99%

Magnetic properties of YBa2Cu3Oy crystal with various oxygen annealing conditions

Watahiki

Jang

Tajima

et al. 1998

Journal of Applied Physics

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It is known that the superconducting properties of YBa2Cu3Oy are strongly dependent on the oxygen content, which affects the anisotropy and the doping level. We measured the magnetic properties of the same YBa2Cu3Oy single crystal in order to systematically study the effect of oxygen annealing condition. The doping level could be controlled simply by changing the annealing temperature. The overdoped samples exhibited a very high irreversibility field of >7 T at 77 K and for the H∥c, although the critical temperature was slightly lower than that of the optimum doped sample. The secondary peak effects are observed for all the samples, however, the source of the peak effect was rather complicated and depended on the annealing conditions.

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Section: Resultsmentioning

confidence: 99%

Magnetic properties of YBa2Cu3Oy crystal with various oxygen annealing conditions

Watahiki

Jang

Tajima

et al. 1998

Journal of Applied Physics

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“…substrate temperature, O 2 partial pressure), we do expect the gold nanoparticles to be causing this effect. This could possibly be due to the fact that the oxygen mobility in YBCO can be increased by gold-doping [26]. Furthermore, we suggest that grain boundaries between Au nanoparticles and surrounding YBCO thin film might enhance the in-diffusion of oxygen, since this process is dominated by surface/grain boundary diffusion [27].…”

Section: Superconducting Properties Of Au Modified Ybcomentioning

confidence: 88%

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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“…A replacement of Cu (1) by Au in the Cu-O chains leads to an increase of the oxygen mobility. 23 An enhanced oxygen mobility favors longer Cu-O chain segments leading to in increase of the charge carrier transfer from the Cu-O chains to the CuO 2 planes. 2 Since more charge carriers can contribute to superconductivity, n s increases while λ ab decreases.…”

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Modifications of the Meissner screening profile in YBa2Cu3O7−δthin films by gold nanoparticles

et al. 2014

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Adding Au nanoparticles to YBa2Cu3O 7−δ thin films leads to an increase of the superconducting transition temperature Tc and the critical current density jc. While the higher jc can be understood in terms of a stronger pinning of the flux vortices at the Au nanoparticles, the enhanced Tc is still puzzling. In the present study, we determined the microscopic magnetic penetration profiles and the corresponding London penetration depths λL in the Meissner state of optimally doped YBa2Cu3O 7−δ thin films with and without Au nanoparticles by low-energy muon spin rotation. By Rutherford backscattering spectrometry, we show that the Au nanoparitcles are distributed over the whole thickness of the thin-film samples. The superfluid density ns ∝ 1/λ 2 L was found to increase in the films containing Au nanoparticles. We attribute this increase of ns to a reduction of the defect density possibly due to defect condensation at the Au nanoparticles.The influence of disorder on cuprate systems is still an open issue. It is known that disorder directly affects the superconducting properties of these systems, but the underlying mechanisms are not fully clarified. 1 In YBa 2 Cu 3 O 7−δ (YBCO), for instance, the charge carrier transfer from the Cu-O chains to the CuO 2 planes is crucial for the appearance of superconductivity. This charge transfer depends strongly on the oxygen order and on the oxygen mobility within the Cu-O chains. 2 Substitution of chain Cu by other metal ions leads generally to a suppression of the superconducting transition temperature T c . 3 Surprisingly, this does not apply to Au. Superconducting quantum interference device (SQUID) and neutron diffraction measurements performed by Cieplak et al. 4,5 show that it is possible to incorporate 10 at.% Au into the structure of polycrystalline YBCO, where Au exclusively replaces the chain Cu(1) atoms. This leads to an increase of T c of about 1.5 K and to an increase of the c-axis lattice constant. The Cu-O bond length between Cu(1) and the oxygen in the Cu-O chains as well as between Cu(1) and the bridging oxygen are enlarged. Previous studies revealed also a lower normal state resistance and a minor influence on the normal state magnetization and on the upper critical field. 6 Recently, it has been demonstrated that Au nanoparticles, incorporated in YBCO thin films, lead to an increase of T c and the critical current density j c (from 4 · 10 7 A/cm 2 to 6 · 10 7 A/cm 2 at 10 K). 7,8 Since YBCO is superconducting above the boiling temperature of nitrogen this is of special interest for applications. A stronger flux pinning of the vortices at the Au nanoparticles causes a higher j c , which is crucial in order to improve superconducting magnetic field sensors 8,9 as used in dc-SQUID gradiometers.Until now little is known about the effect of the inclusion of Au nanoparticles on the microscopic superconducting parameters, such as the superfluid density n s . In the present study we investigated two sets of YBCO thin films with different Au contents by means of low-e...

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Comparison of Au-free versus Au-doped YBa2Cu3O7−δ single crystals

Cited by 15 publications

References 12 publications

Magnetic properties of YBa2Cu3Oy crystal with various oxygen annealing conditions

Magnetic properties of YBa2Cu3Oy crystal with various oxygen annealing conditions

Structural properties of gold modified YBa₂Cu₃O_7−δthin films

Modifications of the Meissner screening profile in YBa2Cu3O7−δthin films by gold nanoparticles

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Comparison of Au-free versus Au-doped YBa2Cu3O7−δ single crystals

Cited by 15 publications

References 12 publications

Magnetic properties of YBa2Cu3Oy crystal with various oxygen annealing conditions

Magnetic properties of YBa2Cu3Oy crystal with various oxygen annealing conditions

Structural properties of gold modified YBa2Cu3O7−δthin films

Modifications of the Meissner screening profile in YBa2Cu3O7−δthin films by gold nanoparticles

Contact Info

Product

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Structural properties of gold modified YBa₂Cu₃O_7−δthin films