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1
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Analysis of Resistive Superconducting Transition of a (Tl_{0.6}Pb_{0.24}Bi_{0.16})(Ba_{0.1}Sr_{0.9})_2Ca_2Cu_3O_{y} Film

100%
Woch W., Chrobak M., Kołodziejczyk A.
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issue 2
389-392
EN
In this paper we analyze the resistive transition as a function of both the temperature and the dc applied magnetic field. We use the two models: first, based on the Ambegaokar and Halperin theory that describes the resistive transitions by the modified Bessel function and second, based on the Anderson and Kim theory represented by the exponential formula. The fits of the models to experimental results show that the freezing into superconducting vortex-glass phase takes place at the same temperature that does not practically depend on the applied magnetic field.
2
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Study of Resistive Superconducting Transition of Bulk (Bi_{0.6}Pb_{0.4})_2Sr_2Ca_2Cu_{3}O_{x}

100%
Woch W., Chrobak M., Zalecki R., Kołodziejczyk A.
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vol. 126
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issue 1
328-329
EN
The temperature widths of the resistive transition as well as the thermal fluctuations of bulk (Bi_{0.6}Pb_{0.4})_2Sr_2Ca_2Cu_{3}O_{x} superconductor with T_{c,50%} = 107.1 K were studied. The applied magnetic field widens the resistive transition according to the following formula: ΔT = CH^{m} + ΔT_{0}. The value of exponent m = 0.44 suggests that there is strong pining of vortices, especially at lower temperatures. The critical exponents λ of the conductivity were calculated using the following equation: Δσ = Kε^{-λ}, with the λ_1 = 1.75 close to the zero critical temperature and λ_2 = 3.77 at higher temperatures. These values were discussed within the available theoretical models.
3
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Resistance and AC Susceptibility of YBCO 1:2:3 Films on Silver Substrates

100%
Zalecki R., Woch W., Chrobak M., Kołodziejczyk A.
Acta Physica Polonica A
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2012
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vol. 121
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issue 4
850-853
EN
The YBa_{2}Cu_{3}O_{δ} films were obtained directly on the polished silver substrates by the sedimentation process. Thickness of these films is of the order of several tens micrometers. The temperature dependences of the resistance and the AC susceptibility of the films were measured and analyzed. The critical temperatures of these specimens vary from 89 K to 91 K and they do not depend on the annealing temperatures. The critical currents were calculated from AC susceptibility measurements using the Bean's model.
4
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AC Susceptibility of YBCO 1:2:3 Films on Silver Substrates

100%
Zalecki R., Woch W., Chrobak M., Kołodziejczyk A.
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vol. 126
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issue 4a
A-13-A-16
EN
The YBa_2Cu_3O_δ films were obtained directly on silver substrates by the sedimentation processes. The thicknesses of these films are of the order of several tens μ. The temperature dependences of the AC susceptibility of the films were measured and analyzed. The critical temperatures of these specimens obtained from the dispersion part of AC susceptibility vary from 89.2 K to 92.5 K. The critical currents were calculated from the absorption part of AC susceptibility using the Bean model. The temperature dependences of the critical currents were fitted using the Ginzburg-Landau strong coupling limit approach.
5
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Penetration Depth of Magnetic Field into YBa₂Cu₃Oₓ Film on Polycrystalline Ag Substrate

100%
Zalecki R., Woch W., Chrobak M., Kołodziejczyk A.
Acta Physica Polonica A
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2015
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vol. 127
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issue 2
272-274
EN
The magnetic field penetration depth into YBa₂Cu₃Oₓ film on polycrystalline Ag substrate with the critical temperature of 90.4 K was determined from the AC susceptibility measurements. The 95 μm thick YBCO film was deposited directly on Ag substrate by the sedimentation process. When the sample is in the Meissner state, the dispersive component of the AC susceptibility as well as its temperature dependence reflects the changes of the penetration depth with the temperature. The penetration depth of this film is found to be 5.4 μm.
6
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Thermal Fluctuations of Bismuth Based 1G Tape

100%
Chrobak M., Woch W., Zalecki R., Kołodziejczyk A.
Acta Physica Polonica A
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2015
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vol. 127
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issue 2
306-308
EN
The thermal fluctuations of bismuth based commercial 1G tape were studied near the critical temperature T_{c}=110.2 K. The detailed analysis of the temperature dependence of resistivity measurements was made in the temperature region from the zero resistance critical temperature up to 300 K. The thermal fluctuations of conductivity were analysed using the Aslamazov-Larkin microscopic approach and the critical exponents were calculated close to the transition temperature.
7
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Critical Currents of Bismuth 1G Tape

100%
Woch W., Zalecki R., Chrobak M., Kołodziejczyk A.
Acta Physica Polonica A
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2015
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vol. 127
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issue 2
315-317
EN
The critical currents of commercial bismuth based superconducting tape were determined in the two ways. In the first one the transport critical current density was measured by the four points method using the dc current power supply at the liquid nitrogen temperature. In the second one the critical current densities were obtained from the absorption part of ac susceptibility measurements using the Bean model near the critical temperature. The temperature dependence of the critical current densities was fitted to take advantage of the Ginzburg-Landau strong-coupling limit approach. Using the fit parameters the critical current density at 77 K was calculated. The critical temperature of this tape (T_{c}= 110.5 K) was determined from the ac susceptibility measurements.
8
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Thermal Fluctuations of (Tl_{0.5}Pb_{0.5})Sr_2(Ca_{0.9}Gd_{0.1})Cu_2O_{z} Bulk Superconductor

100%
Woch W., Chrobak M., Kołodziejczyk A., Gritzner G.
Acta Physica Polonica A
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2012
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vol. 121
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issue 5-6
1059-1062
EN
We report on the critical fluctuations from the magnetoresistance measurements in polycrystalline (Tl_{0.5}Pb_{0.5})Sr_2(Ca_{0.9}Gd_{0.1})Cu_2O_{z} superconductor. The critical exponents have been calculated above the critical temperature T_{c} as well as in the temperatures interval close to the zero resistance critical temperature. Above T_{c} only Gaussian fluctuations have been observed in a three-dimensional fluctuating system. Additionally, far above T_{c} the applied magnetic field induces the crossover from 3D to 2D fluctuating system. At the temperatures range close to the zero critical temperature the properties of the weak links are dominating and the fluctuating phase in each grain becomes long-range ordered as a consequence of the activation of weak links between grains.
9
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Bismuth Valence in a Tl_{0.7}Bi_{0.3}Sr_{1.6}Ba_{0.4}CaCu_{2}O_{y} Superconductor from X-Ray Photoemission Spectroscopy

88%
Zalecki R., Woch W., Kowalik M., Kołodziejczyk A., Gritzner G.
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issue 2
393-395
EN
The X-ray electron photoemission spectra of a Tl_{0.7}Bi_{0.3}Sr_{1.6}Ba_{0.4}CaCu_2O_{y} superconductor were measured with Al K_{α} and Mg K_{α} radiation at room temperature. The Bi 4f spectrum was compared to the same spectra of Bi_{1.75}Pb_{0.35}Sr_{1.9}Ca_{2.05}Cu_{3.05}O_{y} and Tl_{0.6}Pb_{0.4}Sr_{1.6}Ba_{0.4}Ca_2Cu_3O_{y} superconductors. In Bi,Pb-based superconductor only one type of Bi^{3+} ions is present. The Bi 4f spectrum in the Tl,Bi-superconductor consists of two contributions due to the different valences. The component from Bi^{5+} lines is in higher binding energy than from Bi^{3+}. The ratio of trivalent Bi^{3+} to pentavalent Bi^{5+} bismuth ions was calculated from decomposition of the spin-orbit split spectrum of the Bi 4f photoelectrons. The conclusion is that Bi is present in trivalent and in pentavalent form and the ratio of Bi^{3+} to Bi^{5+} is 1.87 ± 0.02.
10
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Penetration Depth of Tl_2Ba_2Ca_2Cu_3O_y and Tl_{0.58}Pb_{0.4}Sr_{1.6}Ba_{0.4}Ca_2Cu_3O_y Bulk Superconductors

88%
Zalecki R., Woch W., Kołodziejczyk A., Konig W., Gritzner G.
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vol. 126
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issue 4a
A-133-A-136
EN
The penetration depths of bulk Tl_2Ba_2Ca_2Cu_3O_y and Tl_{0.58}Pb_{0.4}Sr_{1.6}Ba_{0.4}Ca_2Cu_3O_y superconductors with the critical temperatures 112 K and 114 K, respectively, were determined from the AC susceptibility measurements. When the samples are in the Meissner state, the dispersive components of AC susceptibility as well as their temperature dependences reflect the changes of the penetration depths at various temperatures. In these bulk ceramic superconductors the penetration depths are of the order of few μm and they are comparable to the grains sizes in the ceramics.
11
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Study of Resistive Superconducting Transition of Thallium Based Superconductors

88%
Woch W., Zalecki R., Chrobak M., Kołodziejczyk A., Gritzner G.
Acta Physica Polonica A
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2012
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vol. 121
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issue 4
789-795
EN
A width and shape of resistive transition as well as thermal fluctuations of the thallium based superconductors were analyzed theoretically. The applied magnetic field widens the resistive transition according to the following formula: ΔT=CH^{m}+ΔT_{0}. The exponent m fluctuates around 2/3 and depends on vortex structure and strength of the pinning force. The shape of the resistive transition was fitted by two models: the first one based on Ambegaokar-Halperin theory and the other one based on Anderson-Kim theory expressed by the exponential formula. Critical fluctuations were analyzed on the basis of magnetoresistance measurements results. The critical exponents have been calculated above the critical temperature T_{c} as well as for temperatures close to the zero resistance critical temperature.
12
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Content available

The Irreversibility Fields of (Tl_{0.5}Pb_{0.5}) (Sr_{0.85}Ba_{0.15})_2Ca_2Cu_3O_z Film on Polished Silver Substrate

88%
Woch W., Zalecki R., Kołodziejczyk A., Deinhofer C., Gritzner G.
Acta Physica Polonica A
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2007
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vol. 111
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issue 5
737-743
EN
Superconducting (Tl_{0.5}Pb_{0.5})(Sr_{0.85}Ba_{0.15})_2Ca_2Cu_3O_z film was prepared on a highly polished, untextured silver substrate. A superconducting transition temperature (T_{c,50%}) of 114.7±0.3 K was obtained from the resistance versus temperature measurements for different applied ac currents. The density of the critical current measured by transport method was found to be 11.4×10^3 A/cm^2 at 77 K in the self field. This value is smaller than the value calculated from ac susceptibility data: 53×10^3 A/cm^2 at 77 K. The magnetical broadening of the resistivity transition to the superconducting state was observed. The irreversibility fields of the thallium based film were obtained from magnetoresistive measurements for both parallel to the c-axis and parallel to the $ab$ plane showing the anisotropy according to the magnetic field direction. The irreversibility fields as a function of temperature were successfully fitted by the power law.
13
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Content available

Effect of Magnetic Field on Resistive Transition of Thin Film Thallium Based Superconductors

76%
Woch W., Zalecki R., Kołodziejczyk A., Chmist J., Heiml O., Gritzner G.
Acta Physica Polonica A
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2004
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vol. 106
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issue 5
785-791
EN
The temperature and magnetic field dependences of a.c. resistance of c-axis oriented (Tl_{0.5}Pb_{0.5})(Sr_{0.8}Ba_{0.2})_2Ca _2Cu_3O_x and (Tl_{0.6}Pb_{0.24}Bi_{0.16})(Sr_{0.9}Ba_{0.1})_2Ca_2Cu_3 O_x thin films as well as of (Tl_{0.5}Pb_{0.5})(Sr_{0.8}Ba_{0.2})_2Ca_ 2Cu_3O_x bulk sample from 77 K to room temperature and in magnetic fields from zero to 3000 Oe were measured and analyzed. The magnetic field and temperature dependence of the resistive superconducting transition and irreversibility field were discussed both in the flux-creep model and in the superconducting liquid vortex state model. The temperature width of resistive transition was explained taking advantage of the Ambegaokar and Halperin model of the resistance of superconducting Josephson weak links and barrier of vortex motion presented by Tinkham. The irreversibility field was described by an exponential formula.
14
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Electronic Properties of High-Temperature Superconductor DyBa_{2}Cu_{3}O_{7} from Critical Fields and Specific Heat Studies

76%
Kołodziejczyk A., Kozłowski A., Chmist J., Zalecki R., Ściężor T., Tarnawski Z., Woch W.
Acta Physica Polonica A
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1993
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vol. 84
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issue 1
127-138
EN
The lower and upper critical fields, as well as the specific heat were measured as a function of temperature for good quality DyBa_{2}Cu_{3}O_{7} high-temperature superconductor in the vicinity of superconducting transition temperature T_{c} = 91.2 K. The number of superconducting and normal state electronic quantities were determined basing on the Ginzburg-Landau-Abrikosov-Gorkov theory. It is argued that on the basis of this BCS-like theory one can describe the superconducting properties and, in combination with some information on the electronic structure, also the magnetic properties of high-temperature superconductors.
15
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Kim-Type Critical State Models and Critical Currents of Thallium Based Superconductors

76%
Woch W., Zalecki R., Kołodziejczyk A., Heiml O., Sudra H., Gritzner G.
Acta Physica Polonica A
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2008
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vol. 114
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issue 1
99-106
EN
The two extended formulae in the power form of the Kim critical state model were used to fit the critical currents versus the dc applied magnetic field. Two samples of thallium based superconductors: the (Tl_{0.6}Pb_{0.24}Bi_{0.16})(Sr_{0.9}Ba_{0.1})_2Ca_2Cu_3O_y film on single-crystalline lanthanum aluminate and the bulk (Tl_{0.5}Pb_{0.5})Sr_2(Ca_{1.8}Gd_{0.2})Cu_2O_y were chosen to test the models. The formulae were compared to the percolation model described by the exponential expression. The first model fits the experimental data better for the thallium based film whereas the second approach is better for the thallium based bulk sample.
16
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Magnetization, Susceptibility and Critical Currents of (Tl_{2-x}Re_{x})Ba_{2}CaCu_{2}O_{y} Thin Films

76%
Woch W., Dujavová A., Przewoźnik J., Zalecki R., Kołodziejczyk A., Sojková M., Chromik Š.
Acta Physica Polonica A
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2012
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vol. 121
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issue 4
845-849
EN
The magnetization and the AC susceptibility vs. the temperature as well as the applied magnetic field of the thin film (Tl_{2-x}Re_{x})Ba_{2}CaCu_{2}O_{y} with x=0 and 0.15 on R-plane sapphire substrate with CeO_{2} buffer layer were measured and analyzed. XRD measurements show c-axis as well as a-b plane oriented Tl-1212 and superconducting pure phase. The zero critical temperature of the Tl-Re sample is 99.9 K and is practically the same as the critical temperature of the rhenium free sample: 99.5 K. The Tl-Re superconductor exhibits two peaks of the absorption part of AC susceptibility in the vicinity of the critical temperature in contrary to the rhenium free sample. The first peak placed in higher temperature is related to intragranular properties while the second peak is connected with the intergranular one. The critical current densities versus temperature were calculated from AC susceptibility as well as from the magnetization loops measurements using the Bean's critical state model. The Tl-Re film exhibits the higher critical current in comparison to the rhenium free thallium based film.
17
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Critical Currents, Magnetization and Microwave Absorption of (Tl_{0.5}Pb_{0.5})Sr_2(Ca_{0.8}Gd_{0.2})Cu_2O_{z} Superconductor

76%
Woch W., Niewolski J., Tokarz W., Kołodziejczyk A., Sudra H., Gritzner G.
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issue 2
319-322
EN
The bulk (Tl_{0.5}Pb_{0.5})Sr_2(Ca_{1 - x}Gd_{x})Cu_2O_{z} superconductors with x = 0.1, 0.2 and 0.3 have unique and very interesting magnetic and electrical properties. In this paper we focused our attention on the superconductor with gadolinium content x = 0.2. We measured the magnetic field dependences of the transport critical currents, the microwave absorption as well as the magnetization for different temperatures. The critical temperature of this sample is T_c = 105.3 ± 0.2 K and the transition width Δ T_{90% - 10%} = 3.6 ± 0.2 K. The critical current of this superconductor is J_c = 1 820 ± 10 A/cm^2 at 77 K. The data were analyzed within the frame of the Bean and Kim models as well as the percolation model.
18
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Thermal Fluctuations in YBCO Thin Film on MgO Substrate

76%
Chrobak M., Woch W., Szwachta G., Zalecki R., Gondek Ł., Kołodziejczyk A., Kusiński J.
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EN
The c-axis orientation YBa_2Cu_3O_δ thin film was prepared directly on MgO substrate by the pulse laser deposition. The thickness of the film was 170 nm. The superconducting critical temperature was T_{c50%}=89 K and the width of superconducting transition was Δ T= 1.6 K. Temperature dependence of the critical current of the film was obtained from the temperature dependences of the imaginary part of the AC susceptibility using the Bean model. The critical current density was J_{c}=1.2×10^7 A/cm^{2} at 77 K in the self field. The critical exponents were calculated for several values of the DC applied magnetic field using the temperature dependences of magnetoresistivity. The thermal fluctuations in vicinity of the critical temperature were analysed.
19
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Magnetoresistance Study of c-Axis Oriented YBCO Thin Film

64%
Chrobak M., Woch W., Kowalik M., Zalecki R., Giebułtowski M., Przewoźnik J., Kapusta C., Szwachta G.
Acta Physica Polonica A
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2017
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vol. 131
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issue 4
1018-1020
EN
The c-axis orientation YBa₂Cu₃O_δ thin film was prepared directly on MgO substrate by the pulse laser deposition. The thickness of the film is 170 nm. The superconducting critical temperature is T_{c50%}=87.5 K and the width of superconducting transition is ΔT = 1.8 K. The temperature dependences of magnetoresistance were measured up to 90 kOe. The widths of the transition to the superconducting state versus applied magnetic field were derived and they were fitted using the formula: Δ T=CH^m +Δ T₀. The irreversibility fields as a function of temperature were obtained and fitted by the de Almeida and Thouless-like equation: H_{irr}=H_{irr0}(1-T/T_{c0})^n. The irreversibility field at the liquid nitrogen temperature was calculated and it is H_{irr}=43.8 kOe when the applied magnetic field is parallel to the c-axis.
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