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Wyświetlanie 1-13 z 13
Tytuł:
Metal-Insulator Transition in Zinc-Doped LaSrCuO
Autorzy:
Malinowski, A.
Cieplak, M. Z.
Berkowski, M.
Plesiewicz, W.
Skośkiewicz, T.
Powiązania:
https://bibliotekanauki.pl/articles/2046782.pdf
Data publikacji:
2006-04
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
74.72.-h
71.30.+h
74.25.Fy
Opis:
The magnetotransport in the vicinity of the metal-insulator transition in La$\text{}_{1.85}$Sr$\text{}_{0.15}$Cu$\text{}_{x}$Zn$\text{}_{1-x}$O$\text{}_{4}$ is studied in the mK temperature range. Both longitudinal and transverse magnetoresistance are negative indicating the importance of spin effects. The magnitude of transverse magnetoresistance is larger than the magnitude of longitudinal magnetoresistance, indicating the absence of positive orbital magnetoresistance, in sharp contrast to strongly underdoped La$\text{}_{2-x}$Sr$\text{}_{x}$CuO$\text{}_{4}$. Both transverse and longitudinal magnetoresistance are proportional to the relative change of zero-field conductivity. This suggests that low-temperature localization of carriers may originate in the spin-disorder scattering on the spin droplets around Zn-impurities.
Źródło:
Acta Physica Polonica A; 2006, 109, 4-5; 617-621
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Modelling of Critical Current Density of Sintered Ag Added Bulk MgB₂
Autorzy:
Santosh, M.
Powiązania:
https://bibliotekanauki.pl/articles/1398972.pdf
Data publikacji:
2016-06
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
74.72.-h
74.25.Sv
74.20.-z
Opis:
Magnetic field dependence of critical current density $(J_{c})$ of bulk MgB₂ material at 20 K is reported. The selected sintered MgB₂ materials contained various amounts of silver. The silver added samples possess always a higher critical current density than the silver free ones. The critical current density increased with silver content and continuously decreased with increase of magnetic field. Further, the normalized volume pinning force density,$ f_{p}=F_{p}//F_{p,max}$, versus reduced field $h = H_{a}// H_{irr}$ for silver free and silver added samples suggested that grain boundary pinning is dominant. In essence, the model of thermal activated flux motion was successfully applied to fit the critical current density of the MgB₂ materials.
Źródło:
Acta Physica Polonica A; 2016, 129, 6; 1197-1200
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Modeling of Critical Current Density of Bulk High $T_c$ Superconductors
Autorzy:
Santosh, M.
Powiązania:
https://bibliotekanauki.pl/articles/1205410.pdf
Data publikacji:
2014-08
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
74.72.-h
74.25.Sv
74.20.-z
Opis:
Magnetic field dependence of critical current density $(J_{c})$ of $ErBa_2Cu_3O_y$ thick film "Er-123" and melt textured $GdBa_2Cu_3O_y$ bulk "Gd-123" at liquid nitrogen temperature is reported. Gd-123 exhibits a usual peak effect at magnetic fields around 2 T, while $J_{c}$ of the Er-123 thick film continuously decreases with increasing field. The model of thermally activated flux motion was adopted to fit the critical current density of both Gd-123 and Er-123 materials. It was found that the critical current density of both types of the high $T_{c}$ materials could be modeled by the model of thermally activated flux motion utilizing a combination of two functions; one increasing and another one decreasing with field.
Źródło:
Acta Physica Polonica A; 2014, 126, 3; 808-810
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Inter- and Intragrain Magnetization of Thallium-Based Superconductors
Autorzy:
Tokarz, W.
Kąkol, Z.
Kołodziejczyk, A.
König, W.
Gritzner, G.
Powiązania:
https://bibliotekanauki.pl/articles/2014492.pdf
Data publikacji:
2000-11
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
74.72.Fq
74.72.-h
74.50.+r
Opis:
We report on magnetization and magnetic hysteresis measurements for the (Tl$\text{}_{0.6}$Bi$\text{}_{0.5}$)(Sr$\text{}_{0.9}$Ba$\text{}_{0.1}$)$\text{}_{2}$Ca$\text{}_{2}$Cu$\text{}_{3}$O$\text{}_{y}$ Ag-sheathed superconducting tape as well as for the powdered and bulk (Tl$\text{}_{0.6}$Pb$\text{}_{0.5}$)(Sr$\text{}_{0.9}$Ba$\text{}_{0.1}$)$\text{}_{2}$Ca$\text{}_{2}$Cu$\text{}_{3}$O$\text{}_{y}$ 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.
Źródło:
Acta Physica Polonica A; 2000, 98, 5; 633-636
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Phase Fluctuations and BCS-LP Crossover in 2D Short Coherence Length Superconductors
Autorzy:
Tobijaszewska, B.
Micnas, R.
Powiązania:
https://bibliotekanauki.pl/articles/2012966.pdf
Data publikacji:
2000-03
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
74.20.-z
71.10.Fd
74.20.Fg
74.20.Mn
74.72.-h
Opis:
We study the effects of phase fluctuations in 2D short-coherence length superconductors on the basis of the extended Hubbard model with intersite attraction. In the Kosterlitz-Thouless scenario the critical temperatures for anisotropic pairings were determined and compared with the ones from BCS Hartree-Fock approximation. The Uemura-type plots, i.e. the critical temperature vs. zero temperature phase stiffness, were obtained for extended s-wave and $d_{x^{2}-y^{2}}$-wave pairings. We also discuss the crossover from BCS to local pair superconductivity for d-wave pairing.
Źródło:
Acta Physica Polonica A; 2000, 97, 3; 393-397
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
The Correlation between the Double Helix Quantum Wave in d-Wave Superconductors and Human DNA
Autorzy:
Güven Özdemir, Z.
Aslan Çataltepe, Ö.
Onbaşlı, Ü.
Powiązania:
https://bibliotekanauki.pl/articles/1490548.pdf
Data publikacji:
2012-01
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
74.72.-h
71.18.+y
87.14.gk
Opis:
The effective mass of the quasiparticles in a d-wave superconducting system has been calculated via magnetization measurements done by SQUID by using the advanced derivative method used in our previous works. Phenomenological analogy between the double helix quantum wave, which does exist within the primitive cell of the d-wave superconductor, and the human DNA was previously made. In this work, the numerical proof of the analogy mentioned has been realized by determining the magnitude of the attractive force of d-wave structure and comparing with the magnitude of the force that holds the double strand of human DNA that are both of the same order of $10^{-10}$ N. Moreover, the wavelength of the double helix quantum wave of the superconducting system corresponds to ultraviolet region of the electromagnetic spectrum that exactly coincides with the wavelength which is used for exciting the states in human DNA.
Źródło:
Acta Physica Polonica A; 2012, 121, 1; 13-15
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Superconducting Critical Temperature of Homologous Series of High-T$\text{}_{c}$ Cuprates as a Function of Number of Layers
Autorzy:
Zaleski, T. A.
Kopeć, T. K.
Powiązania:
https://bibliotekanauki.pl/articles/2038383.pdf
Data publikacji:
2004-11
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
74.20.-z
74.72.-h
74.50.+r
Opis:
We have considered a model of n-layer high-temperature cuprates of homologous series like HgBa$\text{}_{2}$Ca$\text{}_{n-1}$Cu$\text{}_{n}$O$\text{}_{2+2n+δ}$ to determine the dependence of the critical temperature T$\text{}_{c}$(n) on the number n of Cu-O planes in an elementary cell. Focusing on the description of the high-temperature superconducting system in terms of the collective phase variables, we have studied a semi-microscopic anisotropic three-dimensional vector XY model of stacked copper-oxide layers with adjustable parameters representing microscopic in-plane and out-of-plane phase stiffnesses. The model captures the layered composition and block structure along c-axis of superconducting homologous series. Implementing the spherical closure relation we have solved the phase XY model exactly with the help of transfer matrix method for vector variables. The calculated dependence of the critical temperature T$\text{}_{c}$(n) on the block size n is monotonic with n.
Źródło:
Acta Physica Polonica A; 2004, 106, 5; 561-567
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Effect of Oxygen Redistribution on Temperature Dependence of Pseudo-Gap in Underdoped $HoBa_{2}Cu_{3}O_{7-δ}$ Single Crystals
Autorzy:
Vovk, R.
Nazyrov, Z.
Obolenskii, M.
Pinto Simoes, V.
Januszczyk, M.
Latosińska, J.
Powiązania:
https://bibliotekanauki.pl/articles/1493662.pdf
Data publikacji:
2011-09
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
74.72.-h
Opis:
The effect of annealing at room temperature on the excess conductivity of oxygen deficient $HoBa_2Cu_{3}O_{7 - δ}$ single crystal is studied. It is shown that there is substantial extension of the interval of linear dependence $ρ_{ab}$ (T) and narrowing of the temperature area of the pseudo-gap regime as a result of annealing. The excess conductivity satisfies the exponential temperature dependence in a wide temperature interval. The temperature dependence of the pseudogap is satisfactorily described by the BCS-BEC theoretical model.
Źródło:
Acta Physica Polonica A; 2011, 120, 3; 512-515
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Breakdown of the De Gennes Scaling in Y$\text{}_{1-x}$Dy$\text{}_{x}$Ni$\text{}_{2}$B$\text{}_{2}$C
Autorzy:
Drzazga, Z.
Winiarska, A.
Winiarski, A.
Kaczorowski, D.
Powiązania:
https://bibliotekanauki.pl/articles/2012891.pdf
Data publikacji:
2000-01
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
74.25.Ha
74.72.-h
82.80.Pv
Opis:
Single crystals of Y$\text{}_{1-x}$Dy$\text{}_{x}$Ni$\text{}_{2}$B$\text{}_{2}$C (1 ≤ x ≤ 0.7) were examined by X-ray diffraction and stoichiometry was attested by XPS measurements. The superconducting transition temperature T$\text{}_{c}$ and Neel temperature T$\text{}_{N}$ were determined by means of magnetisation measurements. A dramatic breakdown of the de Gennes scaling in the Dy-rich compounds was found when T$\text{}_{c}$
Źródło:
Acta Physica Polonica A; 2000, 97, 1; 221-224
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
On the Ratio of the Energy Gap Amplitude to the Critical Temperature for Cuprates
Autorzy:
Szczęiśniak, R.
Durajski, A.
Powiązania:
https://bibliotekanauki.pl/articles/1382034.pdf
Data publikacji:
2014-10
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
74.20.-z
74.20.Fg
74.20.Mn
74.25.Bt
74.72.-h
74.72.Bk
74.72.Jt
Opis:
The model for the cuprates based on the modified electron-phonon pairing mechanism has been tested. For this purpose, the superconductors with high value of the critical temperature have been taken into consideration. In particular: $YBa_{2}Cu_{3}O_{7-y}$, $HgBa_{2}CuO_{4+y}$, $HgBa_{2}Cu_{1-x}Zn_{x}O_{4+y}$, and $HgBa_{2}Ca_{2}Cu_{3}O_{8+y}$. It has been shown that the dependence of the ratio $R_{1}$ ≡ $2Δ_\text{tot}^{(0)}$/$k_{B}T_{C}$ on the doping (p) can be properly predicted in the framework of the presented theory; the symbol $Δ_\text{tot}^{(0)}$ denotes the energy gap amplitude at the temperature of zero kelvin, and $T_{C}$ is the critical temperature. The numerical results have been supplemented by the formula which describes the function $R_{1}(p)$.
Źródło:
Acta Physica Polonica A; 2014, 126, 4a; A-92-A-96
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Negative Magnetoresistance in the Variable-Range-Hopping Transport of Strongly Underdoped La$\text{}_{2-x}$Sr$\text{}_{x}$CuO$\text{}_{4}$
Autorzy:
Malinowski, A.
Cieplak, M. Z.
Berkowski, M.
Guha, S.
Powiązania:
https://bibliotekanauki.pl/articles/2046779.pdf
Data publikacji:
2006-04
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
74.72.-h
74.25.Fy
73.43.Qt
Opis:
The in-plane transport of strongly underdoped La$\text{}_{2-x}$Sr$\text{}_{x}$CuO$\text{}_{4}$ films was examined in the magnetic fields up to 14 T and in temperatures down to 1.6 K. While at high temperatures the samples display metallic-like resistivity, the low-T transport is governed by variable-range-hopping mechanism. Careful analysis shows that the temperature dependence of pre-exponential factor in Mott's variable-range-hopping law may not be neglected and that the density of states at the Fermi level can be effectively expressed as g(E-E$\text{}_{F}$)=N$\text{}_{0}$ (E-E$\text{}_{F}$)$\text{}^{p}$, with a small exponent p of the order of 0.1. In the magnetic field parallel to CuO$\text{}_{2}$ planes one of the variable-range-hopping parameter,ρ$\text{}_{0}$, increases by about 20-25%, while the other one, T$\text{}_{0}$, decreases by about 10-15%, resulting in the decrease in total resistivity. This effect may be related to the decrease of the tunneling barrier between different antiferromagnetic clusters in the presence of magnetic field.
Źródło:
Acta Physica Polonica A; 2006, 109, 4-5; 611-615
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Thermal Fluctuations of $(Tl_{0.5}Pb_{0.5})Sr_2(Ca_{0.9}Gd_{0.1})Cu_2O_{z}$ Bulk Superconductor
Autorzy:
Woch, W.
Chrobak, M.
Kołodziejczyk, A.
Gritzner, G.
Powiązania:
https://bibliotekanauki.pl/articles/1426876.pdf
Data publikacji:
2012-05
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
74.72.-h
74.40.-n
74.20.De
74.25.Ha
Opis:
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.
Źródło:
Acta Physica Polonica A; 2012, 121, 5-6; 1059-1062
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
The Local Order in KTaO$\text{}_{3}$ Admixtured by the Ions of Li$\text{}^{+}$
Autorzy:
Kaszyńska, K.
Trybuła, Z.
Glinchuk, M. D.
Bykov, I. P.
Laguta, V. V.
Powiązania:
https://bibliotekanauki.pl/articles/2043642.pdf
Data publikacji:
2005-08
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
64.70.-p
36.40.Ei
77.22.Gm
74.72.-h
74.76.Bz
Opis:
The low temperature behavior of the KTaO$\text{}_{3}$ type incipient ferroelectric crystals is of constant interest. The quantum fluctuations reduce the transition to the ferroelectric state in these crystals. It is possible that the small amount of the dopant Li$\text{}^{+}$ can lead, through the elastic interactions, to local glass-like short-range order or even to the relaxor ferroelectric order for x>2.6%. We presented that the low lithium doped x=0.005 KTaO$\text{}_{3}$ crystals exhibit the dielectric dispersion ofε andε", suggesting the glass-like behavior in the low temperature range.
Źródło:
Acta Physica Polonica A; 2005, 108, 2; 379-383
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
    Wyświetlanie 1-13 z 13

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