Intrinsic microstrains and normal-phase flicker noise in YBa2Cu3O7 epitaxial films grown on various substrates

Bobyl, A. V.; Gaevski, Mikhail; Karmanenko, S. F.; Kutt, R.N.; Suris, R. A.; Khrebtov, I. A.; Tkachenko, A. D.; Morosov, A. I.

doi:10.1063/1.365898

Cited by 34 publications

(21 citation statements)

References 42 publications

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“…The size of the area where the coherent scattering of xray wave is established has been found to be 30-100Å for YBCO films. 8,33 This value defines the lower limit for r c . It is in agreement with the value r c ≈ 30Å for the size of T c -uniform fragment in YBCO film deduced from analysis of experimental data on voltage noise in the superconducting transition region.…”

Section: Resultsmentioning

confidence: 99%

“…σ hom s is the Cooper pair conductivity for homogeneous sample given by the expressions (8) and (9) obtained on the basis of UD model. The conductivity σ inh of the inhomogeneous sample is determined by EMA formula (14) with f (T c ) being Gaussian distribution function (15), and local conductivities defined as sum of the superconducting, σ hom s , and normal, σ n , contributions.…”

Section: H − T Diagramsmentioning

confidence: 99%

“…6 T c increase due to edge dislocations and low-angle grain boundaries was calculated to be ∼ 1 K. 7 Spatial variations of the c-axis lattice parameter revealed by x-ray studies in YBCO films with almost uniform oxygen content also suggest stress-induced T cinhomogeneity. 8 Presence of T c -inhomogeneity manifests itself in various HTSC properties. Temperature dependence of the depinning current density in YBCO crystals implies that pinning sites are induced by spatial variations of T c .…”

Section: Introductionmentioning

confidence: 99%

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Temperature and magnetic-field dependence of the conductivity ofYBa2Cu3O
Shantsev
¹
,
Gaevski
²
,
Suris
³

et al. 1999
Phys. Rev. B
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Temperature and magnetic-field dependence of the conductivity of YBa 2 Cu 3 O 7−δ films in the vicinity of superconducting transition: Effect of T C -inhomogeneity Temperature and magnetic field dependences of the conductivity of YBa2Cu3O 7−δ films in the transition region are analyzed taking into account spatial inhomogeneity in transition temperature, Tc. (i) An expression for the superconducting contribution to conductivity, σs(T, H, Tc), of a homogeneous superconductor for low magnetic fields, H ≪ Hc2 (0) (ii) The error in σs(T, H, Tc) occurring due to the presence of Tc-inhomogeneity is calculated and plotted on an H − T plane diagram. These calculations use an effective medium approximation and a Gaussian distribution of Tc. (iii) Measuring the temperature dependences of a voltage, induced by a focused electron beam, we determine spatial distributions of the critical temperature for YBa2Cu3O 7−δ microbridges with a 2 µm resolution. A typical Tc-distribution dispersion is found to be ≈1 K. For such dispersion, error in σs(T, H, Tc) due to Tc-inhomogeneity exceeds 30% for magnetic fields H < 1 T and temperatures |T − Tc| < 0.5 K . (iv) Experimental R(T, H) dependences of resistance are well described by a numerical solution of a set of Kirchoff equations for the resistor network based on the measured spatial distributions of Tc and the expression for σs(T, H, Tc).

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Section: Resultsmentioning

confidence: 99%

Section: H − T Diagramsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

Temperature and magnetic-field dependence of the conductivity ofYBa2Cu3O
Shantsev
¹
,
Gaevski
²
,
Suris
³

et al. 1999
Phys. Rev. B
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“…A uniform oxygen distribution in YBa 2 Cu 3 O 7Ϫ␦ films has also been observed earlier. 1,2 It is probably a consequence of a high diffusion coefficient of oxygen in the YBa 2 Cu 3 O 7Ϫ␦ lattice. Thus, we can focus on variations in the cation composition only.…”

Section: A Chemical Composition Variationmentioning

confidence: 99%

Spatially resolved studies of chemical composition, critical temperature, and critical current density of a YBa2Cu3O7−δ thin film

Gaevski

Bobyl

Shantsev

et al. 1998

Journal of Applied Physics

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Spatially-resolved studies of a YBa2Cu3O 7−δ thin film bridge using electron probe microanalysis (EPMA), low-temperature scanning electron microscopy (LTSEM), and magneto-optical flux visualization (MO) have been carried out. Variations in chemical composition along the bridge were measured by EPMA with 3 µm resolution. Using LTSEM the spatial distributions of the critical temperature, Tc, and of the local transition width, ∆Tc, were determined with 5 µm resolution. Distributions of magnetic flux over the bridge in an applied magnetic field have been measured at 15 and 50 K by magneto-optical technique. The critical current density jc as a function of coordinate along the bridge was extracted from the measured distributions by a new specially developed method. Significant correlations between jc, Tc, ∆Tc and cation composition have been revealed. It is shown that in low magnetic fields deviation from the stoichiometric composition leads to a decrease in both Tc and jc. The profile of jc follows the Tc-profile on large length scales and has an additional fine structure on short scales. The profile of jc along the bridge normalized to its value at any point is almost independent of temperature.

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“…To obtain reliable results ®lms with high T c and a low density of other phases were chosen. The existence of only one perfect structure phase of was con®rmed by means of double (triple) crystal diffractometry [27]. Also investigation of the ®lm surface morphology for the presence of inclusions was carried out.…”

Section: Procedures For Determination Of the Composition Of Htsc Filmmentioning

confidence: 99%

Study of Thin Films of High Temperature Superconductors Based on YBaCuO by EPMA

et al. 2000

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An analytical model of an effective atomic number, Z eff , for simultaneous calculation of composition and thickness of ®lms on substrates that allows for backscattering processes is presented. Comparison of dependencies of 9(&z) parameters for ®lm elements on electron beam energy, on atomic numbers of a ®lm and a substrate and on ®lm thickness was done. The errors inherent in EPMA have been determined by comparing experimental data obtained on YBa 2 Cu 3 O 7Àx bulk crystals with model calculations. Possibility of EPMA as an effective technique for investigation of spatially inhomogeneous objects was demonstrated by studying the correlation between composition and local superconducting properties (values of critical temperature and critical current) of these ®lms.The discovery of high temperature superconductivity (HTSC) has resulted in the development of the technology of YBa 2 Cu 3 O 7Àx epitaxial ®lms and in different fundamental and applied studies of their structural and electrophysical properties. The prototypes of practically all known planar devices of the microelectronics have been developed on the base of these ®lms. However, it has been found that even the best YBa 2 Cu 3 O 7Àx ®lms contain signi®cant amounts of different defects and are spatially nonuniform in terms of both their electrophysical properties and composition [1±3]. As a result HTSC microelectronics devices degrade fast, and the yield of those suitable for operation is low [4].Thus, a pressing necessity arose to create technology for the production of high quality YBa 2 Cu 3 O 7Àx ®lms and to develop local high accuracy techniques for determining the composition of the multicomponent structures of the ®lm-substrate type. The use of the EPMA technique has de®nite merits compared with other techniques for the analysis: high spatial resolution of analysis ($ 3 mm), precise observation of the analysed place, availability of well-developed techniques for quanti®cation, and also low sensitivity to artefacts. However, the weaknesses of EPMA technique should be noted: (i) low sensitivity of the analysis (b 0.1±0.001 wt.7), (ii) low possibility to ®x the small difference between concentrations (analytical sensitivity), more then 0.1±0.37 at the concentration of several tens of wt.7 (iii) poor in-depth resolution. Moreover, the procedure for determination of the composition of the ®lms of thicknesses smaller than the X-ray generation depth (R x ) (HTSC ®lms are related just to this class of object) are not up to now suf®ciently developed. The present work is a review devoted to our investigations of HTSC YBa 2 Cu 3 O 7Àx epitaxial ®lms and contains a thorough experimental veri®cation on the correlations between composition and local superconducting properties. Procedure for Determining Composition and Thickness of Films (Z eff Model)In the case when the ionization path of an electron is greater than the ®lm thickness, the use of a model

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Intrinsic microstrains and normal-phase flicker noise in YBa2Cu3O7 epitaxial films grown on various substrates

Cited by 34 publications

References 42 publications

Temperature and magnetic-field dependence of the conductivity ofYBa2Cu3O
Shantsev
¹
,
Gaevski
²
,
Suris
³

et al. 1999
Phys. Rev. B
Self Cite
7
0
7
0
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Temperature and magnetic-field dependence of the conductivity ofYBa2Cu3O
Shantsev
¹
,
Gaevski
²
,
Suris
³

et al. 1999
Phys. Rev. B
Self Cite
7
0
7
0
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Spatially resolved studies of chemical composition, critical temperature, and critical current density of a YBa2Cu3O7−δ thin film

Study of Thin Films of High Temperature Superconductors Based on YBaCuO by EPMA

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Intrinsic microstrains and normal-phase flicker noise in YBa2Cu3O7 epitaxial films grown on various substrates

Cited by 34 publications

References 42 publications

Temperature and magnetic-field dependence of the conductivity ofYBa2Cu3OShantsev1, Gaevski2, Suris3 et al. 1999Phys. Rev. BSelf Cite7070View full textAdd to dashboardCite

Temperature and magnetic-field dependence of the conductivity ofYBa2Cu3OShantsev1, Gaevski2, Suris3 et al. 1999Phys. Rev. BSelf Cite7070View full textAdd to dashboardCite

Spatially resolved studies of chemical composition, critical temperature, and critical current density of a YBa2Cu3O7−δ thin film

Study of Thin Films of High Temperature Superconductors Based on YBaCuO by EPMA

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Temperature and magnetic-field dependence of the conductivity ofYBa2Cu3O
Shantsev
¹
,
Gaevski
²
,
Suris
³

et al. 1999
Phys. Rev. B
Self Cite
7
0
7
0
View full text Add to dashboard Cite

Temperature and magnetic-field dependence of the conductivity ofYBa2Cu3O
Shantsev
¹
,
Gaevski
²
,
Suris
³

et al. 1999
Phys. Rev. B
Self Cite
7
0
7
0
View full text Add to dashboard Cite