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

100%

Woch W., Zalecki R., Kołodziejczyk A., Chmist J., Heiml O., Gritzner G.

Acta Physica Polonica A

2004

vol. 106

issue 5

785-791

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.

Electronic Properties of High-Temperature Superconductor DyBa_{2}Cu_{3}O_{7} from Critical Fields and Specific Heat Studies

100%

Kołodziejczyk A., Kozłowski A., Chmist J., Zalecki R., Ściężor T., Tarnawski Z., Woch W.

Acta Physica Polonica A

1993

vol. 84

issue 1

127-138

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.

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

84%

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

Acta Physica Polonica A

2004

vol. 106

issue 5

665-680

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.

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3 Acta Physica Polonica A

2 2004

1 1993

3 Chmist J.

3 Kołodziejczyk A.

2 Gritzner G.

2 Tarnawski Z.

2 Woch W.

2 Zalecki R.

1 Heiml O.

1 Kellner K.

1 Kolwicz-Chodak L.

1 Kozłowski A.

1 Krop K.

1 Przewoźnik J.

1 Ściężor T.

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

Electronic Properties of High-Temperature Superconductor DyBa_{2}Cu_{3}O_{7} from Critical Fields and Specific Heat Studies

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