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Tytuł:
XPS Study of Superconducting $LiTi_2O_4$ and $LiTi_{2-x}Cu_{x}O_4$ Sol-Gel Derived Powders and Thin Films
Autorzy:
Łapinski, M.
Kościelska, B.
Winiarski, A.
Sadowski, W.
Powiązania:
https://bibliotekanauki.pl/articles/1374065.pdf
Data publikacji:
2014-10
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
74.78.-w
81.20.Fw
Opis:
In this work X-ray photoelectron studies of lithium titanate and copper doped lithium titanate are presented. Both, powder and thin films samples were prepared by sol-gel method. After preparation, the samples were heated in argon atmosphere at various temperatures in a range from 500 °C to 600 °C for 20 h. The crystalline structure of the samples was investigated by X-ray diffraction, while the oxidation states of the elements were examined by X-ray photoelectron spectroscopy method. X-ray diffraction measurements confirmed spinel phase of all manufactured samples. However it is well known that electrical and superconducting properties of lithium titanate are strongly correlated not only with structure, but also with oxidation state of Ti ions. X-ray photoelectron spectroscopy investigations revealed mixture of $Ti^{3+}$ and $Ti^{4+}$ ions, although the $Ti^{3+}$/$Ti^{4+}$ ratio is much smaller than $1/2$ needed for superconductivity. In this work dependence between calcination temperature as well as amount of Cu dopant and $Ti^{3+}$/$Ti^{4+}$ proportion are reported.
Źródło:
Acta Physica Polonica A; 2014, 126, 4a; A-107-A-110
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Ultrathin Niobium in the Si/Nb/Si Trilayers
Autorzy:
Zaytseva, I.
Abal'oshev, O.
Dłużewski, P.
Minikayev, R.
Cieplak, Marta
Zhu, L.
Chien, C.
Powiązania:
https://bibliotekanauki.pl/articles/1374193.pdf
Data publikacji:
2014-10
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
74.78.-w
74.70.Ad
74.25.-q
Opis:
We study magnetotransport properties of the Si/Nb/Si trilayers, in which the thickness of niobium, d, changes from 1.1 nm to 50 nm, while the thickness of Si is fixed at 10 nm. The niobium films are amorphous for d < 4 nm, while in thicker films the alligned polycrystalline grains are formed. We observe that the Hall coefficient changes sign into negative in the films with d < 1.6 nm. We also find that in the ultrathin films the magnetic field induces a transition from the superconducting into a metallic phase with the resistance smaller than the normal-state resistance.
Źródło:
Acta Physica Polonica A; 2014, 126, 4a; A-140-A-144
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Ultrathin NbN Films for Superconducting Single-Photon Detectors
Autorzy:
Słysz, W.
Guziewicz, M.
Borysiewicz, M.
Domagała, J.
Pasternak, I.
Hejduk, K.
Rzodkiewicz, W.
Ratajczak, J.
Bar, J.
Węgrzecki, M.
Grabiec, P.
Grodecki, R.
Węgrzecka, I.
Sobolewski, R.
Powiązania:
https://bibliotekanauki.pl/articles/1504147.pdf
Data publikacji:
2011-07
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
74.62.Bf
74.78.-w
81.15.Cd
81.15.Jj
Opis:
We present our research on fabrication and structural and transport characterization of ultrathin superconducting NbN layers deposited on both single-crystal $Al_2O_3$ and Si wafers, and $SiO_2$ and $Si_3N_4$ buffer layers grown directly on Si wafers. The thicknesses of our films varied from 6 nm to 50 nm and they were grown using reactive RF magnetron sputtering on substrates maintained at the temperature 850°C. We have performed extensive morphology characterization of our films using the X-ray diffraction method and atomic force microscopy, and related the results to the type of the substrate used for the film deposition. Our transport measurements showed that even the thinnest, 6 nm thick NbN films had the superconducting critical temperature of 10-12 K, which was increased to 14 K for thicker films.
Źródło:
Acta Physica Polonica A; 2011, 120, 1; 200-203
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Transport Properties of Nitrided $VN-SiO_{2}$ Sol-Gel Derived Films
Autorzy:
Kościelska, B.
Powiązania:
https://bibliotekanauki.pl/articles/1431203.pdf
Data publikacji:
2012-04
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
81.20.Fw
74.78.-w
74.70.Ad
Opis:
This work presents transport properties of $xVN-(100-x)SiO_{2}$ (where x = 90, 80, 70, 60 mol%) films. The films were prepared by thermal nitridation of sol-gel derived $V_{2}O_{3}-SiO_{2}$ (in proper molar ratio) coatings. The coatings obtained by sol-gel method are especially suitable for the ammonolysis because of their porosity. The microporous structure allows both a significant incorporation of nitrogen and its distribution through the film. The nitridation process of $V_{2}O_{3}-SiO_{2}$ coatings leads to the formation of disordered structures, with VN metallic grains dispersed in the matrix of insulating $SiO_{2}$. The critical temperatures of the superconducting transition of the samples $T_\text{conset}$ are about 7.5 K.
Źródło:
Acta Physica Polonica A; 2012, 121, 4; 744-746
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Time-Reversal Invariant Topological Superconductivity in Quasi-One-Dimensional Structures
Autorzy:
Mammadova, S.
Nakhmedov, E.
Alekperov, O.
Powiązania:
https://bibliotekanauki.pl/articles/1398788.pdf
Data publikacji:
2016-04
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
74.78.-w
71.10.Pm
71.70.Ej
74.50.+r
Opis:
It is shown that a time-reversal invariant topological superconductivity can be realized in a quasi-one-dimensional structure, which is fabricated by filling the superconducting materials into the periodic channel of dielectric matrices like zeolite and asbestos under high pressure. The topological superconducting phase sets up in the presence of large spin-orbit interactions when s-wave intra-wire and d-wave inter-wire pairings take place. Kramers pairs of Majorana bound states emerge at the edges of each wire. The time-reversal topological superconductor belongs to DIII class of symmetry with a Z₂ invariant.
Źródło:
Acta Physica Polonica A; 2016, 129, 4; 800-802
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Thermal Fluctuations of Bismuth Based 1G Tape
Autorzy:
Chrobak, M.
Woch, W.
Zalecki, R.
Kołodziejczyk, A.
Powiązania:
https://bibliotekanauki.pl/articles/1385435.pdf
Data publikacji:
2015-02
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
74.72.-h
74.78.-w
74.40.-n
74.62.-c
Opis:
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.
Źródło:
Acta Physica Polonica A; 2015, 127, 2; 306-308
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Thermal Fluctuations in YBCO Thin Film on MgO Substrate
Autorzy:
Chrobak, M.
Woch, W.
Szwachta, G.
Zalecki, R.
Gondek, Ł.
Kołodziejczyk, A.
Kusiński, J.
Powiązania:
https://bibliotekanauki.pl/articles/1374789.pdf
Data publikacji:
2014-10
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
74.72.-h
74.78.-w
74.40.-n
74.62.-c
Opis:
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.
Źródło:
Acta Physica Polonica A; 2014, 126, 4a; A-88-A-91
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
The Evolution of Superconducting Phase $MgB_x$
Autorzy:
Łoś, Sz.
Kempiński, W.
Piekara-Sady, L.
Andrzejewski, B.
Jurga, W.
Kaszyńska, K.
Piekoszewski, J.
Werner, Z.
Barlak, M.
Powiązania:
https://bibliotekanauki.pl/articles/1812318.pdf
Data publikacji:
2008-07
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
74.70.-b
74.78.-w
Opis:
Thin layers of $MgB_x$ were studied in order to define evolution of superconducting phase after Mg ions implantation into boron substrate. Three fluencies of energies 140, 80, and 40 keV were used to establish proper stoichiometry to synthesize homogeneous $MgB_2$ film. Additionally, the annealing processes were carried out at temperatures 400, 500, and 600°C in a furnace in an atmosphere of flowing $Ar-4%H_2$ gas mixture. The quality of the superconducting material was examined by magnetically modulated microwave absorption, and magnetic and resistivity measurements. The results showed that $T_c$ becomes higher with increasing annealing temperature. However, the fraction of superconducting phase decreases, due to partial evaporation of Mg ions and their deeper migration into boron substrate.
Źródło:
Acta Physica Polonica A; 2008, 114, 1; 179-184
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Technology of Ultrathin NbN and NbTiN Films for Superconducting Photodetectors
Autorzy:
Guziewicz, M.
Slysz, W.
Borysiewicz, M.
Kruszka, R.
Sidor, Z.
Juchniewicz, M.
Golaszewska, K.
Domagala, J.
Rzodkiewicz, W.
Ratajczak, J.
Bar, J.
Wegrzecki, M.
Sobolewski, R.
Powiązania:
https://bibliotekanauki.pl/articles/1492719.pdf
Data publikacji:
2011-12
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
74.62.Bf
74.78.-w
81.15.Cd
81.15.Jj
Opis:
We report fabrication and characterization of ultrathin NbN and NbTiN films designed for superconducting photodetectors. Our NbN and NbTiN films were deposited on $Al_2O_3$ and Si single-crystal wafers by a high-temperature, reactive magnetron sputtering method and, subsequently, annealed at 1000°C. The best, 18 nm thick NbN films deposited on sapphire exhibited the critical temperature of 15.0 K and the critical current density as high as ≈ 8 × $10^6$ A/$cm^2$ at 4.8 K.
Źródło:
Acta Physica Polonica A; 2011, 120, 6A; A-076-A-079
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Superconductivity of $MgB_2$ Layers Prepared on Silicon Substrate by Implantation of Magnesium Ions into Boron Substrate
Autorzy:
Trybuła, Z.
Kempiński, W.
Łoś, Sz.
Kaszyńska, K.
Trybuła, M.
Piekoszewski, J.
Werner, Z.
Barlak, M.
Powiązania:
https://bibliotekanauki.pl/articles/1536977.pdf
Data publikacji:
2010-08
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
74.70.-b
74.78.-w
Opis:
The results of investigation of the $MgB_2$ layers prepared on silicon substrate by implantation of Mg ions into boron substrate are presented. After implantation the annealing processes were carried out at temperatures 673 K, 773 K, and 873 K in a furnace in an atmosphere of flowing Ar-4%$H_2$ gas mixture. The samples were characterized by: four-probe electric conductivity measurements and magnetically modulated microwave absorption. Our results showed that due to silicon substrate the diffusion of implanted Mg ions into boron materials should be limited, and the superconducting phase forms a continuous $MgB_2$ layer and the resistivity for all samples fall down to zero below $T_{c}$. The transition temperature $T_{c}$ becomes higher with increasing annealing temperature: $T_{c}$=18 K (for annealing at $T_{A}$=673 K), $T_{c}$=20 K (for annealing at $T_{A}$=773 K), and $T_{c}$=27 K (for annealing at $T_{A}$=873 K).
Źródło:
Acta Physica Polonica A; 2010, 118, 2; 323-325
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Superconductivity Near Transition to Insulating State in MoC Ultrathin Films Studied by Subkelvin STM
Autorzy:
Szabó, P.
Neilinger, P.
Trgala, M.
Grajcar, M.
Samuely, P.
Powiązania:
https://bibliotekanauki.pl/articles/1372334.pdf
Data publikacji:
2014-07
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
74.50.+r
74.78.-w
74.81.-g
Opis:
We study the homogeneously disordered MoC thin films with thicknesses of 10 and 5 nm and the superconducting transition temperatures near 6 and 4 K, significantly decreased as compared to the bulk $T_{c}$=8.32 K due to a disorder. The scanning tunnelling spectroscopy reveals in the thicker sample a BCS superconducting energy gap Δ with a broadening parameter Γ equal to about 10 per cent of Δ. Remarkably, Γ increases with temperature. The thinner, more disordered sample shows a gapped superconducting density of states but without any coherence peaks at the gap edge, which could not be approximated by the BCS DOS. Moreover, the reduced DOS around the Fermi level persists above the resistive transition temperature reminding the pseudo-gap known from high-$T_{c}$ cuprates.
Źródło:
Acta Physica Polonica A; 2014, 126, 1; 368-369
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Superconducting Regions and Kondo Effect of MgB$\text{}_{2}$ Formed by Implantation of Magnesium Ions into Boron Substrate
Autorzy:
Trybuła, Z.
Kempiński, W.
Andrzejewski, B.
Piekara-Sady, L.
Kaszyński, J.
Trybuła, M.
Piekoszewski, J.
Stanisławski, J.
Barlak, M.
Richter, E.
Powiązania:
https://bibliotekanauki.pl/articles/2046803.pdf
Data publikacji:
2006-04
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
74.70.-b
74.78.-w
Opis:
The results of investigation of the polycrystalline boron implanted by magnesium and argon plasma pulse treatment are presented. The four-probe electric conductivity measurements and magnetically modulated microwave absorption showed the presence of superconducting islands below the temperature of 25 K. Below T=23 K we detected the Kondo effect, a logarithmic increase in the resistivity as the temperature is lowered, due to iron impurity.
Źródło:
Acta Physica Polonica A; 2006, 109, 4-5; 657-660
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Superconducting Properties of $VN-SiO_{2}$ Sol-Gel Derived Thin Films
Autorzy:
Kościelska, B.
Yuzephovich, O.
Bengus, S.
Winiarski, A.
Sadowski, W.
Łapiński, M.
Powiązania:
https://bibliotekanauki.pl/articles/1431327.pdf
Data publikacji:
2012-04
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
81.20.Fw
74.78.-w
Opis:
In this work studies of structure and superconducting properties of $VN-SiO_{2}$ films are reported. The films were obtained through thermal nitridation (ammonolysis) of sol-gel derived $V_{2}O_{3}-SiO_{2}$ coatings (in a proper $V_{2}O_{3}//SiO_{2}$ ratio) at 1200°C. This process leads to the formation of disordered structure with VN metallic grains dispersed in the insulating $SiO_{2}$ matrix. The structural transformations occurring in the films as a result of ammonolysis were studied using X-ray photoelectron spectroscopy (XPS). The critical superconducting parameters are obtained. The magnetoresistance at high magnetic fields has been investigated.
Źródło:
Acta Physica Polonica A; 2012, 121, 4; 832-835
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Superconducting Properties of $NbN-SiO_2$ Sol-Gel Derived Thin Films
Autorzy:
Kościelska, B.
Yuzephovich, O.
Bengus, S.
Witkowska, A.
Powiązania:
https://bibliotekanauki.pl/articles/1537127.pdf
Data publikacji:
2010-08
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
81.20.Fw
74.78.-w
74.70.Ad
Opis:
This work presents results of superconducting properties studies of $xNbN-(100-x)SiO_2$ (where x = 80 mol%) films of the thickness from 450 to 1950 nm. The films were prepared by thermal nitridation of sol-gel derived $xNb_2O_5-(100-x)SiO_2$ coatings. The nitridation process of $Nb_2O_5-SiO_2$ coatings leads to the formation of weakly disordered structures, with NbN metallic grains dispersed in the matrix of insulating $SiO_2$. All the samples in the normal state exhibit negative temperature coefficient of resistivity. Superconducting transition was not observed for the sample 450 nm thick. To examine the influence of magnetic field on superconducting properties of the films, the resistance versus temperature of 1350 and 1650 nm thick samples was measured in high magnetic fields. Resistive superconducting transitions are broadened due to the magnetic flux creep. The perpendicular upper critical magnetic fields for 1350 and 1650 thick samples are about 4.4 T. The critical temperatures of the superconducting transitions are about 4.5 K. Specific features of the magnetic field induced superconductor-insulator transition are found.
Źródło:
Acta Physica Polonica A; 2010, 118, 2; 383-385
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Superconducting Layers by Gallium Implantation and Short-Term Annealing in Semiconductors
Autorzy:
Fiedler, J.
Heera, V.
Voelskow, M.
Mücklich, A.
Reuther, H.
Skorupa, W.
Gobsch, G.
Helm, M.
Powiązania:
https://bibliotekanauki.pl/articles/1400477.pdf
Data publikacji:
2013-05
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
74.78.-w
Opis:
Superconducting layers in silicon and germanium are fabricated via gallium implantation through a thin $SiO_2$ cover layer and subsequent rapid thermal annealing. Gallium accumulation at the $SiO_2//Si$ and $SiO_2//Ge$ interfaces is observed but no pure gallium phases were found. In both cases superconducting transition occurs around 6-7 K which can be attributed to the metallic conducting, gallium rich interface layer. However, the superconducting as well as the normal-state transport properties in gallium overdoped silicon or germanium are different.
Źródło:
Acta Physica Polonica A; 2013, 123, 5; 916-919
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł

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