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Wyszukujesz frazę "74.25.Bt" wg kryterium: Temat


Tytuł:
$Ru_3Sn_7$: Phonon Reference for Superconducting $Mo_3Sb_7$
Autorzy:
Tran, V.
Miiller, W.
Powiązania:
https://bibliotekanauki.pl/articles/1810300.pdf
Data publikacji:
2009-01
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
65.40.-b
72.15.Eb
74.25.Kc
74.25.Bt
72.15.Qm
Opis:
In order to search for phonon reference for dimer-gapped superconducting $Mo_3Sb_7$, measurements of specific heat $(C_p(T))$ and electrical resistivity (ρ(T)) of $Ru_3Sn_7$ were performed in the temperature range 2-300 K. The phonon part of $C_p(T)$ and ρ(T) of $Ru_3Sn_7$ can satisfactorily be explained describing the spectrum with one Einstein and two Debye modes. We found $Θp_{E}$ ≈ 100 K, $Θp_{D1}$ ≈ 185 K and $Θp_{D2}$ ≈298 K. The magnetic specific heat of $Mo_3Sb_7$ exhibits a sharp maximum at T*= 50 K, below which follows a gap function. Magnetic resistivity increases as -lnT with decreasing temperature and shows maximum at T*.
Źródło:
Acta Physica Polonica A; 2009, 115, 1; 83-85
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
AC Microcalorimetry of Superconducting $MgCNi_3$ Single Crystals
Autorzy:
Kačmarčík, J.
Pribulová, Z.
Samuely, P.
Marcenat, C.
Klein, T.
Jang, D.
Lee, H.
Lee, S.
Powiązania:
https://bibliotekanauki.pl/articles/1813689.pdf
Data publikacji:
2008-01
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
74.70.Ad
74.25.Bt
Opis:
The low-temperature specific heat of single-crystal samples of superconducting $MgCNi_3$ with typical dimensions 200 μm were measured for the first time. A computer controlled ac microcalorimeter using an optical fiber and an infrared light-emitting diode as the heat source was used down to 2 K at magnetic fields up to 8 T. The specific heat data suggest a moderate coupling in $MgCNi_3$.
Źródło:
Acta Physica Polonica A; 2008, 113, 1; 363-366
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Characteristics of the Eliashberg Formalism on the Example of High-Pressure Superconducting State in Phosphor
Autorzy:
Duda, A.
Szczęśniak, R.
Sowińska, M.
Domagalska, I.
Powiązania:
https://bibliotekanauki.pl/articles/1398651.pdf
Data publikacji:
2016-08
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
74.20.Fg
74.25.Bt
74.62.Fj
Opis:
The work describes the properties of the high-pressure superconducting state in phosphor: p∈ {20, 30, 40, 70} GPa. The calculations were performed in the framework of the Eliashberg formalism, which is the natural generalization of the BCS theory. The exceptional attention was paid to the accurate presentation of the used analysis scheme. With respect to the superconducting state in phosphor it was shown that the observed not-high values of the critical temperature ([T_{C}]_{p=30GPa}^\text{max}=8.45 K) result not only from the low values of the electron-phonon coupling constant, but also from the very strong depairing Coulomb interactions. Additionally the inconsiderable strong-coupling and retardation effects force the dimensionless ratios $R_{Δ}$, $R_{C}$, and $R_{H}$ - related to the critical temperature, the order parameter, the specific heat, and the thermodynamic critical field - to take the values close to the BCS predictions.
Źródło:
Acta Physica Polonica A; 2016, 130, 2; 649-654
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Characterization of Novel High-Pressure Close-Packed Superconducting Phase of Boron
Autorzy:
Szczęśniak, D.
Szczęśniak, R.
Powiązania:
https://bibliotekanauki.pl/articles/1385110.pdf
Data publikacji:
2015-02
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
74.25.Bt
74.62.Fj
74.20.Fg
Opis:
We report study on the thermodynamic properties of the novel high-pressure superconducting phase of boron with hexagonal P6₃/mcm structure. Our analysis is conducted at the pressure of p=400 GPa, which is motivated by the highest value of the superconducting transition temperature $(T_{C})$ observed previously under such conditions for the P6₃/mcm boron. Our investigations of the thermodynamic properties are performed within the Eliashberg formalism, due to the strong-coupling character of the considered material. In particular, we calculate the thermodynamic properties of the superconducting state which allows us to determine the values of the characteristic dimensionless parameters; the zero-temperature energy gap to the critical temperature, the ratio of the specific heats, as well as the ratio connected with the zero-temperature thermodynamic critical field.
Źródło:
Acta Physica Polonica A; 2015, 127, 2; 254-256
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Growth Rate of $YBa_2Cu_3O_7$ Bulk Crystals in $Y_{1.5}Ba_2Cu_3$ System with $CeO_2$ Addition
Autorzy:
Zmorayová, K.
Šefčiková, M.
Volochová, D.
Kalmanová, M.
Piovarči, S.
Diko, P.
Powiązania:
https://bibliotekanauki.pl/articles/1418272.pdf
Data publikacji:
2012-10
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
74.25.Bt
74.62.Bf
74.62.Dh
81.10.Fq
81.20.Ev
81.30.Fb
Opis:
The growth rate of $Y_1Ba_2Cu_3O_{x}$ bulk single grain (in fact single crystal) superconductors in the system with composition $Y_{1.5}Ba_2Cu_3O_{x}$ and $CeO_2$ addition was studied in the temperature range 991-1001°C. It is shown that the growth rate of bulk crystal is different for a- and c-growth direction. Slower measured growth rate in studied system than in pure $Y_1Ba_2Cu_3O_{x}$ is related to the composition shift to the three-phase field containing CuO.
Źródło:
Acta Physica Polonica A; 2012, 122, 4; 725-727
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Microstructure and Properties of Y-123/Y-211 Bulk Superconductors with $BaCeO_{3}$ and $BaO_{2}$ Addition
Autorzy:
Zmorayova, K.
Antal, V.
Radusovska, M.
Piovarci, S.
Volochova, D.
Diko, P.
Powiązania:
https://bibliotekanauki.pl/articles/1371616.pdf
Data publikacji:
2014-07
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
74.25.Bt
74.25.Ha
74.62.Bf
74.62.Dh
81.10.Fq
81.30.Fb
Opis:
$YBa_{2}Cu_{3}O_{7-δ}$ (YBCO) bulk single-grain superconductors were prepared by a TSMG process. $CeO_{2}$, $BaCeO_{3}$ and $BaO_{2}$ powders were added to nominal composition $Y_{1.5}Ba_{2}Cu_{3}O_{7}$ with the aim to refine $Y_{2}BaCuO_{5}$ (Y-211) secondary particles. Added powders were refined by milling in a friction milling and characterized by X-ray powder difractometry. Thermal properties of the systems were characterized by DTA. Microstructure of samples was studied by PLM. Successful refinement of Y-211 particles size was confirmed by IP measurements. Transition temperatures and field dependences of the magnetic moment for further determination of the critical current densities were obtained using a VSM.
Źródło:
Acta Physica Polonica A; 2014, 126, 1; 366-367
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Monte Carlo Study of a Periodically Pinned 2D Superconductor
Autorzy:
Rezlescu, N.
Anghelache, R.
Ciobotaru, I.
Powiązania:
https://bibliotekanauki.pl/articles/1955503.pdf
Data publikacji:
1997-02
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
64.60.Fr
75.10.Hk
74.25.Bt
Opis:
We show that a natural assumption on the moving mechanism of vortices in a periodically pinned, two-dimensional superconductor in the mixed state is the basis for a n-clock-like model. The pinning points are considered to be centered in each unit cell of the superconducting lattice. This property enables one to use a discrete version of the XY model used in the simulations focusing on the melting of the Abrikosov lattice of vortices in a system of Josephson arrays. A Monte Carlo study performed on the corresponding Hamiltonian in a field given by a filling factor of f=1/2 exhibits two phase transitions, at the temperatures T$\text{}_{c1}$≈0.325 and T$\text{}_{m}$≈0.65. The numerical estimation of the Challa parameters for both transitions indicates their continuous nature. The physical meaning of the lower transition is the expulsion of the magnetic field from the superconducting system, i.e. the Meissner effect. The physical equivalent of the upper transition is the melting of the pinned vortex lattice.
Źródło:
Acta Physica Polonica A; 1997, 91, 2; 337-340
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
On the Magnetic Penetration Depth in Superconducting Ultrathin Lead Films
Autorzy:
Durajski, A.
Szczęśniak, R.
Powiązania:
https://bibliotekanauki.pl/articles/1032804.pdf
Data publikacji:
2017-04
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
74.20.Fg
74.25.Bt
74.62.Fj
Opis:
In the present paper, we report a theoretical study of the magnetic London penetration depth in ultrathin Pb films consisting of five to ten monolayers. Our calculations were performed within the framework of the strong-coupling approach. We observed that for thin films, the thermodynamic parameter exhibits an oscillatory behaviour connected with a quantum size effect. Moreover, we proved that the London penetration depth of Pb films cannot be correctly described using the Bardeen-Cooper-Schrieffer theory of superconductivity due to the strong-coupling and retardation effects. The Eliashberg theory, used in this paper, goes beyond the BCS theory to include these effects which allows to describe the superconducting state on the quantitative level.
Źródło:
Acta Physica Polonica A; 2017, 131, 4; 1051-1053
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:
On the Thermodynamic Critical Field for the $K_3C_{60}$ and $Rb_3C_{60}$ Fullerides
Autorzy:
Durajski, A.
Szczęśniak, R.
Powiązania:
https://bibliotekanauki.pl/articles/1371531.pdf
Data publikacji:
2014-07
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
74.20.Fg
74.25.Bt
74.62.Fj
Opis:
In the paper the temperature dependence of the thermodynamic critical field ($H_c$) for the alkali-metal-doped fullerides $K_3C_{60}$ and $Rb_3C_{60}$ has been considered. The numerical calculations have been conducted in the framework of the Migdal-Eliashberg formalism. It has been shown that the obtained numerical values of $H_c$ agree with the experimental data. Finally, the dimensionless ratio: $R_{H}$ ≡ $T_cC^{N}$ ($T_c$)/$H_c^{2}(0)$ has been calculated, where $T_c$ is the critical temperature and $C^{N}$ denotes the specific heat in the normal state. The theoretical analysis has proved that for the considered fullerides the parameter $R_{H}$ is beyond the BCS prediction. In particular: $R_{H}$=0.143 for $K_3C_{60}$, and $R_{H}$=0.145 for $Rb_3C_{60}$.
Źródło:
Acta Physica Polonica A; 2014, 126, 1; 342-343
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Pressure Dependence of the Thermodynamic Critical Field in Francium
Autorzy:
Pach, P.
Szczęśniak, R.
Durajski, A.
Powiązania:
https://bibliotekanauki.pl/articles/1384843.pdf
Data publikacji:
2015-02
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
74.20.Fg
74.25.Bt
74.62.Fj
Opis:
In the paper, the values of the thermodynamic critical field $(H_{C})$ for francium have been calculated. It has been assumed the wide range of the pressure: p∈ ⟨7.2; 14⟩ GPa. The analysis has been performed in the framework of the strong-coupling formalism. It has been predicted that the value of the ratio $H_{C}(0)$/√ρ(0) increases with the increasing pressure from 3.08 meV to 5.84 meV, where ρ(0) denotes the electron density of states at the Fermi level. The dimensionless parameter $T_{C}C^{N}(T_{C})$/$H²_{C}(0)$ is smaller than in the BCS theory and decreases with pressure from 0.150 to 0.141. The symbol $T_{C}$ represents the critical temperature and $C^{N}$ is the specific heat for the normal state.
Źródło:
Acta Physica Polonica A; 2015, 127, 2; 231-233
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Remarks on the First Hundred Years of Superconductivity
Autorzy:
Wysokiński, K.
Powiązania:
https://bibliotekanauki.pl/articles/1431128.pdf
Data publikacji:
2012-04
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
01.65.+g
74.25.Bt
74.25.F-
Opis:
On the occasion of centenary of superconductivity discovery I recall some facts from the first period and attempts to understand the phenomenon. It turns out that most famous physicists of the first half of XX century have tried to solve the puzzle. Bardeen, Cooper and Schrieffer succeeded in 1957. The BCS theory successfully described all known facts and offered new predictions, which soon have been confirmed experimentally contributing to the widespread acceptance of the theory. It have found applications in nuclear physics, theory of neutron stars and cold atomic gases. The discoveries of new superconductors in the last thirty years show that simple BCS model is not enough to understand new unconventional superconductors. The studies of superconductors develop vividly and still fascinate new generations of physicists working in such diverse fields as material science and string theory.
Źródło:
Acta Physica Polonica A; 2012, 121, 4; 721-725
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Reversible Magnetization of Melt-Processed NEG-123 Superconductor
Autorzy:
Jirsa, M.
Rameš, M.
Muralidhar, M.
Kacmarcik, J.
Marcenat, Ch.
Powiązania:
https://bibliotekanauki.pl/articles/1535270.pdf
Data publikacji:
2010-11
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
74.25.Ha
74.25.Bt
74.25.Op
Opis:
Specific heat of superconducting electrons was measured in a melt-processed $(Nd_{0.33}Eu_{0.38}Gd_{0.28})Ba_2Cu_3O_{y}$ superconductor (NEG-123) with 5 mol% of Gd-211, 1 wt% Ag, and 0.035 mol% of Zn. The thermodynamic characteristics of this compound are still not well known. From calorimetric measurements the reversible magnetization, critical fields, penetration depth, and coherence length were deduced. In the vicinity of $T_{c}$, the reversible magnetic moment was additionally measured by means of SQUID.
Źródło:
Acta Physica Polonica A; 2010, 118, 5; 1022-1023
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Specific Heat and Magnetoresistance of Y-, Tl- and Bi-Type High-Temperature Superconductors
Autorzy:
Zalecki, R.
Kozłowski, A.
Kołodziejczyk, A.
Gritzner, G.
Mair, M.
Powiązania:
https://bibliotekanauki.pl/articles/1955838.pdf
Data publikacji:
1997-02
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
74.72.Fq
74.25.Ha
74.72.Bk
74.72.Hs
74.25.Bt
Opis:
Specific heat of polycrystalline DyBa$\text{}_{2}$Cu$\text{}_{3}$O$\text{}_{7}$ and Tl$\text{}_{0.58}$Pb $\text{}_{0.42}$Sr$\text{}_{1.6}$Ba$\text{}_{0.4}$Ca$\text{}_{2}$Cu$\text{}_{3}$O$\text{}_{9}$ samples, as well as the single crystal of Bi$\text{}_{2}$Sr$\text{}_{2}$CaCu$\text{}_{2}$O$\text{}_{8}$ 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$\text{}_{c}$ have been observed. In contrary, for Bi-specimen only a rounded maximum within a broad interval around T$\text{}_{c}$ has been detected. Magnetoresistance measurements as a function of temperature just below T$\text{}_{c}$ 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.
Źródło:
Acta Physica Polonica A; 1997, 91, 2; 431-434
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Specific Heat Study of Superconductivity in $Cu_{0.061}TiSe_{2}$
Autorzy:
Kačmarčík, J.
Pribulová, Z.
Pal'uchová, V.
Husaníková, P.
Karapetrov, G.
Komanický, V.
Samuely, P.
Powiązania:
https://bibliotekanauki.pl/articles/1371314.pdf
Data publikacji:
2014-07
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
72.80.Ga
74.25.Bt
71.45.Lr
Opis:
In $TiSe_{2}$ a charge-density-waves order is continuously suppressed by copper doping and superconductivity appears. We report a calorimetric study performed on the superconducting single crystal of $Cu_{0.061}TiSe_{2}$ with $T_{c}$=2.8 K, measured by the ac technique at low temperatures down to 0.6 K and magnetic fields up to 2 T. Sharp specific heat anomaly at the superconducting transition is found. The temperature dependence of the electronic specific heat and the angular dependence of the critical temperature, measured at a fixed magnetic field, consistently indicate on the existence of a single s-wave superconducting gap with a coupling strength of 2Δ/$k_{B}T_{c}$=3.6, close to BCS limit.
Źródło:
Acta Physica Polonica A; 2014, 126, 1; 322-323
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł

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