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1

Temperature and Magnetic Field Dependences of Critical Current of Thallium-Based Superconducting Films

100%

Zalecki R., Kołodziejczyk A., Heiml O., Gritzner G.

Acta Physica Polonica A

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2006

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vol. 109

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issue 4-5

669-674

EN

The critical current densities of three superconducting thallium-based films, prepared by screen printing, were measured as a function of temperature and applied magnetic field. The degradation of critical current densities was investigated for two different magnetic field orientations with respect to the sample plane - parallel and perpendicular.

2

Photoemission Electronic States of Thallium- and Bismuth-Based Superconductors

100%

Zalecki R., Kołodziejczyk A., König J. W., Gritzner G.

Acta Physica Polonica A

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2000

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vol. 98

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issue 5

513-524

EN

X-ray photoemission spectra the core-levels as well as the X-ray photoemission spectra and ultraviolet photoemission spectra from the valence bands of the (Tl_{0.6}Pb_{0.5})(Sr_{0.9}Ba_{0.1}) Ca_{2}Cu_{3}O_{y} and (Bi_{1.75}Pb_{0.35})Sr_{1.9}Ca_{2.05}Cu_{3.05}O_{y} superconductors were measured and analyzed. Special attention was paid to the valence band X-ray photoemission spectra and ultraviolet photoemission spectra, the Cu 2p core-level X-ray photoemission spectra and the Cu L_{2,3}-M_{4,5}M_{4,5} and O K-L_{2,3}L_{2,3} Auger spectra. Both Cu 2p_{3/2} and Cu 2p_{1/2} core-level lines consisted of two spin-orbit split main lines accompanied with the two satellite lines. The charge transfer energy Δ from the oxygen ligand to the copper 3d^{9} states and the hopping integral t were estimated from the energy separation between the main line and the satellite line taking advantage of the local cluster model calculations and their extension to high-temperature superconductors. The Coulomb correlation on-site energy U_{dd} of two electrons in the same copper orbital and U_{pp} of two electrons in the oxygen orbital as well as the correlation energy U_{cd} of the 2p core hole - 3d electron interaction have been estimated from the Auger electron spectra and the valence band spectra. They are: U_{dd}=6.0±0.5eV, of U_{pp}≅ 10±1eV and of U_{cd}≅ 8.0±0.5eV nearly the same for both the Tl- and Bi-compounds. We conclude that these compounds are the charge transfer strongly-correlated metals.

3

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.

4

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.

5

Specific Heat and Magnetoresistance of Y-, Tl- and Bi-Type High-Temperature Superconductors

88%

Zalecki R., Kozłowski A., Kołodziejczyk A., Gritzner G., Mair M.

Acta Physica Polonica A

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1997

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vol. 91

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issue 2

431-434

EN

Specific heat of polycrystalline DyBa_{2}Cu_{3}O_{7} and Tl_{0.58}Pb _{0.42}Sr_{1.6}Ba_{0.4}Ca_{2}Cu_{3}O_{9} samples, as well as the single crystal of Bi_{2}Sr_{2}CaCu_{2}O_{8} have been measured within the temperature interval from 50 to 250 K. For Dy- and Tl-specimens the pronounced jump in specific heat and apparent contribution from Gaussian fluctuations of superconducting order parameter close to T_{c} have been observed. In contrary, for Bi-specimen only a rounded maximum within a broad interval around T_{c} has been detected. Magnetoresistance measurements as a function of temperature just below T_{c} have been carried out for Dy- and Tl-samples and the slopes of upper critical fields have been determined. The data have been analysed within a frame of Ginzburg-Landau-Abrikosov- Gorkov theory with additional Gaussian-like fluctuation term. The electronic specific heat coefficients γ, and the coherence length χ have been obtained.

6

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.

7

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.

8

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.

9

Inter- and Intragrain Magnetization of Thallium-Based Superconductors

88%

Tokarz W., Kąkol Z., Kołodziejczyk A., König W., Gritzner G.

Acta Physica Polonica A

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2000

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vol. 98

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issue 5

633-636

EN

We report on magnetization and magnetic hysteresis measurements for the (Tl_{0.6}Bi_{0.5})(Sr_{0.9}Ba_{0.1})_{2}Ca_{2}Cu_{3}O_{y} Ag-sheathed superconducting tape as well as for the powdered and bulk (Tl_{0.6}Pb_{0.5})(Sr_{0.9}Ba_{0.1})_{2}Ca_{2}Cu_{3}O_{y} superconductors. For the investigated tape and bulk specimens the low field magnetization showed a deviation from the ideal linear M(H) dependence, which was attributed to the superposition of inter- and intragrain superconducting currents. Fitting of the theoretical magnetization curves to the experimental data allowed for the independent determination of the intragrain critical current densities for the superconducting grains and intergrain critical current densities for the weak link system at 77K.

10

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.

11

Magnetic and Transport Properties of La_{0.67}Pb_{0.33}(Mn_{1-x}Co_x)O_3

76%

Mihalik M., Kavečanský V., Maťaš S., Zentková M., Ammer J., Kellner K., Gritzner G.

Acta Physica Polonica A

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2008

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vol. 113

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issue 1

251-254

EN

Detailed studies of temperature dependences of magnetization, AC susceptibility and electrical resistance were performed on La_{0.67}Pb_{0.33}(Mn_{1-x}Co_x)O_3 ceramics with x = 0.01 and 0.1. Typical features of both compounds are the hysteretic behavior between the zero-field-cooled magnetization regime and the field-cooled magnetization regime, a very weak field dependence of a maximum in zero-field-cooled magnetization and practically no frequency dependence of the peak in AC susceptibility χ"(T). Anomalies in the electrical resistance connected with the ferromagnetic transition at T_C, the insulator-metal transitions at T_p and the re-entrant metal-isolator transition at T* are field dependent pointing to magnetic origin of these transitions. Colossal magnetoresistance was observed in both compounds.

12

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.

13

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.

14

Structural, Thermal, Magnetic, and Transport Properties of (La_{2/3}Ca_{1/3})(Mn_{1-x}Sn_x)O_{3-δ} Compounds

64%

Przewoźnik J., Chmist J., Kolwicz-Chodak L., Tarnawski Z., Kołodziejczyk A., Krop K., Kellner K., Gritzner G.

Acta Physica Polonica A

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2004

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vol. 106

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issue 5

665-680

EN

The structural, magnetic, and electrical transport properties of Sn-doped manganite La_{0.67}Ca_{0.33}Mn_{1-x} Sn_xO_{3-δ} (x=0, 0.01, 0.03, andδ≈0.06) compounds were studied using X-ray powder diffraction, scanning electron microscopy, AC susceptometer and vibrating sample magnetometer measurements as well as four-probe resistance measurements. The specific heat was measured by the heat-pulse method. The Curie temperature T_C and the metal-insulator transition temperature T_{M-I} decreased nonlinearly with increasing Sn content. The T_C and T_{M-I} values, for the x=0, 0.01, and 0.03 compounds were separated by 18.2 K, 66.3 K, and 10 K, respectively. The resistivity above T_C for all of these compounds followed the Mott variable-range-hopping model. This allowed the estimation of the localization lengths of 2.2Å (x = 0), 1.33Å (x=0.01) and 1.26Å (x=0.03). The x=0 and x=0.01 compounds exhibited anomalies of R(T) at corresponding T_C and allowed the separation of the magnitude of the purely magnetic contribution to the resistance which for x=0 was≈5 .7Ω and for x=0.01,≈22 .4Ω. The specific heat of the Sn-free sample exhibited a sharp peak at T_C. With increasing Sn content the peak at T_C broadened and the area under the peak decreased. For x= 0.03 the peak was hardly detectable. Our results on La_{0.67}Ca_{0.33} Mn_{1-x}Sn_xO_3 reveal that a small substitution of Sn^{4+} for Mn^{4+} suppresses double exchange interactions and strongly affects the magnetic, thermal, and transport properties of the parent compound.

Refine search results

Temperature and Magnetic Field Dependences of Critical Current of Thallium-Based Superconducting Films

Photoemission Electronic States of Thallium- and Bismuth-Based Superconductors

Thermal Fluctuations of (Tl_{0.5}Pb_{0.5})Sr_2(Ca_{0.9}Gd_{0.1})Cu_2O_{z} Bulk Superconductor

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

Specific Heat and Magnetoresistance of Y-, Tl- and Bi-Type High-Temperature Superconductors

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

Study of Resistive Superconducting Transition of Thallium Based Superconductors

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

Inter- and Intragrain Magnetization of Thallium-Based Superconductors

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

Magnetic and Transport Properties of La_{0.67}Pb_{0.33}(Mn_{1-x}Co_x)O_3

Kim-Type Critical State Models and Critical Currents of Thallium Based Superconductors

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

Structural, Thermal, Magnetic, and Transport Properties of (La_{2/3}Ca_{1/3})(Mn_{1-x}Sn_x)O_{3-δ} Compounds