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Tytuł:
Muon Spin Rotation Studies of Doping in High-T$\text{}_{c}$ Superconductors
Autorzy:
Niedermayer, Ch.
Powiązania:
https://bibliotekanauki.pl/articles/2011019.pdf
Data publikacji:
1999-08
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
74.25.Ha
74.62.Dh
76.75.+i
Opis:
Muon spin rotation studies on high temperature superconducting cuprates will be reviewed. After an introduction to the technique, studies on the superfluid density will be described and the universal variation of the superfluid density n$\text{}_{s}$ as a function of p will be presented. Important exceptions will be discussed, such as the YBa$\text{}_{2}$Cu$\text{}_{3}$O$\text{}_{7-δ}$ system, where, besides the intrinsically superconducting CuO$\text{}_{2}$ planes, an interlayer may be metallised (here the CuO chains) which consequently contributes to a significant enhancement in superfluid density and associated improvement in technologically interesting properties such as flux pinning and critical current density. Evidence for an unconventional pairing state, possibly with d-wave symmetry, is presented from studies of the rapid suppression of superfluid density due to the substitution of structural inhomogeneities (such as Zn) that introduce strong scattering centers within the CuO$\text{}_{2}$ planes. Finally, the phase diagram of the antiferromagnetic correlations and, in particular, their coexistence with the superconducting state, will be discussed in terms of muon spin rotation experiments in zero external magnetic field.
Źródło:
Acta Physica Polonica A; 1999, 96, 2; 213-227
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Against Quantum Noise
Autorzy:
Ekert, A.
Macchiavello, Ch.
Powiązania:
https://bibliotekanauki.pl/articles/1968509.pdf
Data publikacji:
1998-01
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
89.70.+c
03.65.Bz
Opis:
This is a brief description of how to protect quantum states from dissipation and decoherence that arise due to uncontrolled interactions with the environment. We discuss recoherence and stabilization of quantum states based on two techniques known as "symmetrization" and "quantum error correction". We illustrate our considerations with the most popular quantum-optical model of the system-environment interaction, commonly used to describe spontaneous emission, and show the benefits of quantum error correction in this case.
Źródło:
Acta Physica Polonica A; 1998, 93, 1; 63-76
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Photochemical Reduction and Oxidation of Cerium(IV) Porphyrin Sandwich Complexes
Autorzy:
Radzki, S.
Giannotti, Ch.
Powiązania:
https://bibliotekanauki.pl/articles/1945650.pdf
Data publikacji:
1996-08
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
82.50.Fv
Opis:
Irradiation of cerium(IV) complex of octaethyl bisporphyrin Ce[OEP(-2]$\text{}_{2}$ with visible light, in the presence of CCl]$\text{}_{4}$ as an electron acceptor, leads to their photooxidation and π cation radical formation. The process was followed using electron absorption and magnetic circular dichroism spectroscopy. Electronic configuration in neutral mono- and bisporphyrin (sandwich) complexes were compared to the one of the neutral species. Photoirradiation of sandwich octaethyl- and tetraphenyl bisporphyrins, in the presence of an electron donor (triethylamine) results in their photoreduction on different pathways. Formation of the [Ce(III)(TPP)(-2)TPP(-2)]¯ and [Ce(III)(OEP)(-1)(OEP)(-2)] complexes was followed by absorption and electron spin resonance spectroscopy.
Źródło:
Acta Physica Polonica A; 1996, 90, 2; 385-391
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Temperature Dependence of the Preexponential Factors of the Field Emission Flicker Noise Cross-Correlation Function for W(110)K
Autorzy:
Dąbrowski, A. M.
Kleint, Ch.
Powiązania:
https://bibliotekanauki.pl/articles/1920678.pdf
Data publikacji:
1992-04
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
79.70.+q
68.90.+g
Opis:
In a field emission tube with two probe-holes the cross-correlation functions of current fluctuations from potassium submonolayers on tungsten have been investigated. The measurements were carried out in the temperature range of 290-430 K and with coverages between 0.05 and 0.87. The experimental correlation curves were approximated by a sum of three exponential functions revealing three components with different time constants τ$\text{}_{i}$ and amplitudes R. The temperature dependence of the amplitudes R$\text{}_{2}$ and R$\text{}_{3}$ is discussed in terms of collective flip-flop processes.
Źródło:
Acta Physica Polonica A; 1992, 81, 4-5; 583-588
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Positronium in Metal-Oxide Powders Studied with Age. The Age-Momentum Correlation Technique
Autorzy:
Van Waeyenberge, B.
Dauwe, Ch.
Powiązania:
https://bibliotekanauki.pl/articles/2028957.pdf
Data publikacji:
2001-11
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
36.10.Dr
41.75.Fr
78.70.Bj
Opis:
For the first time positronium is investigated in fine powders of MgO and Al$\text{}_{2}$O$\text{}_{3}$ using age-momentum correlation technique based on a relativistic positron beam. The application of this technique for investigating the interaction of positronium with the grain surfaces is discussed and compared with other techniques. The previously reported interaction of the positronium with paramagnetic centres is further studied. A qualitative interpretation of the spectra is given. In the Al$\text{}_{2}$O$\text{}_{3}$ samples we found some unexpected behaviour of the conversion quenching of ortho-positronium at irradiation induced paramagnetic surface defect.
Źródło:
Acta Physica Polonica A; 2001, 100, 5; 707-715
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Powder Metallurgy Manufacturing of Carbon-Free Precipitation Hardened High Speed Steels
Autorzy:
Danninger, H.
Harold, Ch.
Gierl, Ch.
Ponemayr, H.
Daxelmueller, M.
Simancik, F.
Izdinsky, K.
Powiązania:
https://bibliotekanauki.pl/articles/1537970.pdf
Data publikacji:
2010-05
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
81.05.Bx
81.40.-z
Opis:
Carbon-free steels of the type Fe-Co-(Mo,W) have been known for long to attain very high hardness levels through precipitation hardening. However, the classical ingot metallurgy route tended to result in brittle materials. Here it is shown that the powder metallurgy route through mixing of elemental powders, pressing and sintering results in materials with excellent combination of hardness and transverse rupture strength if the processing parameters are adjusted accordingly, in particular sintering and heat treatment being critical stages that should result in chemically homogeneous and fine-grained microstructure. If properly processed, these steel grades offer excellent red hardness since the hardening intermetallic phases are much less sensitive to overaging than the secondary carbides in standard high speed steels.
Źródło:
Acta Physica Polonica A; 2010, 117, 5; 825-830
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Diffusion of Potassium on the W(112) Plane Preadsorbed by Ni Atoms: Field Emission Current Fluctuations - Autocorrelation Study
Autorzy:
Biernat, T.
Błaszczyszyn, R.
Kleint, Ch.
Powiązania:
https://bibliotekanauki.pl/articles/2027391.pdf
Data publikacji:
2001-06
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
79.70.+q
68.37.Vj
68.43.Jk
05.40.Ca
Opis:
Diffusion of potassium adsorbate on the W(112) plane with preadsorbed nickel was investigated by means of the autocorrelation function of field emission current fluctuations. A comparison of the experimental autocorrelation function with that of a theoretical calculation by Gesley and Swanson gives the surface diffusion coefficient of potassium. From its temperature dependence the diffusion activation energy at several Ni pre-coverages for a constant potassium coverage (Θ$\text{}_{K}$=0.4) is derived. The dependence of the activation energy for potassium surface diffusion on the nickel coverage - first reduction and then an increase with increasing Ni coverage - is observed. This is in agreement with the results obtained from the spectral analysis of the field emission current fluctuations of the same system. The decrease is understood to be a result of the smoothing effect caused by Ni atoms on the W(112) plane.
Źródło:
Acta Physica Polonica A; 2001, 99, 6; 665-672
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Reflection Electron Energy Loss Spectroscopy of Alkali Metals on Silicon
Autorzy:
Kleint, Ch.
Abd El-Halim, S. M.
Powiązania:
https://bibliotekanauki.pl/articles/1892213.pdf
Data publikacji:
1992-01
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
73.20.-r
79.20.Fv
79.20.Hx
Opis:
In an extended introduction studies of alkali adsorption on clean silicon surfaces are shortly reviewed and recent achievements are outlined. The main part describes our investigations of lithium and potassium adsorption by reflection electron energy loss spectroscopy (REELS). Beside (electronic) valence electron excitations also core losses of both silicon and these alkali metals were observed in the ionization loss spectroscopy mode (ILS). Additional information has been obtained by Auger electron spectroscopy (AES) and measurements of work function changes (WFC). The spectra of Li and K adsorption on the Si(100) plane show considerable differences which will be discussed in detail. By simulation of the REEL potassium spectra within the density of states (DOS) model using the Si(100)2 × 1 K DOS by R. Ramirez the origin of the 8.4 and 12.5 eV loss peaks can be traced to band structure features. In addition the known K peaks at 18.1, 20 and 22 eV are confirmed and their behaviour with increasing primary energy E$\text{}_{p}$, was investigated. While the K 3p-K 4s transition corresponding to the 18.1 eV loss increases with E$\text{}_{p}$, the dipole-forbidden K 3p-K 4p transition (20 eV) decreases. Shifts in the loss energy of these peaks as well as in the core loss energies at 295 and 296.8 eV are observed and explained by charge transfer.
Źródło:
Acta Physica Polonica A; 1992, 81, 1; 47-65
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Dynamics of Nematogenic Molecules with Transverse Component of Dipole Moment
Autorzy:
Douali, R.
Czechowski, G.
Legrand, Ch.
Jadżyn, J.
Powiązania:
https://bibliotekanauki.pl/articles/2037273.pdf
Data publikacji:
2004-04
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
64.70.Md
77.84.Nh
77.22.Gm
Opis:
The paper presents the results of studies of the dielectric relaxation of nematic 4'-butyloxy-3-fluoro- 4-isothiocyanatotolane, performed for different values of the angle between the probing electric field E and the macroscopic orientation of the sample (the director n) forced by the magnetic field B. Due to a relatively large transverse component of the dipole moment of 4'-butyloxy- 3-fluoro-4-isothiocyanatotolane, the studies allowed one to interpret consistently the dielectric relaxation spectra connected with the molecular rotation around the long axis.
Źródło:
Acta Physica Polonica A; 2004, 105, 4; 365-371
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Theory of Ultrafast Demagnetization after Femtosecond Laser Pulses
Autorzy:
Fähnle, M.
Illg, Ch.
Haag, M.
Teeny, N.
Powiązania:
https://bibliotekanauki.pl/articles/1384049.pdf
Data publikacji:
2015-02
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
75.78.Jp
75.30.Ds
75.40.Gb
Opis:
Experimentally it has been found that a ferromagnetic metallic film is strongly demagnetized within few hundred fs after exposure to a fs laser pulse. The theories of this ultrafast demagnetization are reviewed, especially the influence of scatterings of the excited electrons at phonons and at magnons. The calculations for phonons and magnons are performed by the ab initio spin-density-functional electron theory for Ni and Fe, and they are based on Fermi's golden rule for transition rates. The application of this rule on the fs time scale is critically discussed in view of results from quantum-kinetic density-matrix calculations. It is shown that the experimentally observed demagnetization rates cannot be explained by spin-flip scatterings of electrons exclusively at phonons or exclusively at magnons. A combination of individual spin-flip electron-phonon and spin-flip electron-magnon processes is shown to be a potential candidate for the explanation of ultrafast demagnetization.
Źródło:
Acta Physica Polonica A; 2015, 127, 2; 170-175
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Magnetization Relaxation in CdMnS
Autorzy:
Witowski, A. M.
Kutter, Ch.
Mac, W.
Wyder, P.
Powiązania:
https://bibliotekanauki.pl/articles/1929759.pdf
Data publikacji:
1993-10
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
76.30.Fc
Opis:
The static magnetization measurements and relaxation of magnetization data for two Cd$\text{}_{1-x}$Mn$\text{}_{x}$S samples with different composition are presented. The magnetization is described by the modified Brillouin function. The magnetization relaxation shows unusual composition dependence. This behavior is explained by cross-relaxation to the unknown fast relaxing centers introduced during growth.
Źródło:
Acta Physica Polonica A; 1993, 84, 4; 798-800
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Secure Communication with a Publicly Known Key
Autorzy:
Beige, A.
Englert, B.-G.
Kurtsiefer, Ch.
Weinfurter, H.
Powiązania:
https://bibliotekanauki.pl/articles/2030467.pdf
Data publikacji:
2002-03
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
03.67.Dd
42.79.Sz
Opis:
We present a scheme for direct and confidential communication between Alice and Bob, where there is no need for establishing a shared secret key first, and where the key used by Alice even will become known publicly. The communication is based on the exchange of single photons and each and every photon transmits one bit of Alice's message without revealing any information to a potential eavesdropper.
Źródło:
Acta Physica Polonica A; 2002, 101, 3; 357-368
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Measuring the Energy Landscape in Single Semiconductor Nanowires
Autorzy:
Smith, L.
Jackson, H.
Yarrison-Rice, J.
Jagadish, Ch.
Powiązania:
https://bibliotekanauki.pl/articles/1419516.pdf
Data publikacji:
2012-08
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
73.22.-f
73.43.Fj
73.50.Gr
73.50.Pz
73.63.-b
78.30.Fs
78.35.+c
78.55.-m
78.67.-n
Opis:
With the ability to design and control the physical structure of nanostructures to tune their electronic properties, it is increasingly important to measure the electronic structure of single nanostructures. Here we describe a number of experimental techniques for measuring the electronic structure of single semiconductor nanowires. The advantages, disadvantages and limitations of these methods will be described.
Źródło:
Acta Physica Polonica A; 2012, 122, 2; 316-320
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:
Direct Observation of Localized Modes in an Open Disordered Microwave Cavity
Autorzy:
Mortessagne, F.
Laurent, D.
Legrand, O.
Sebbah, P.
Vanneste, Ch.
Powiązania:
https://bibliotekanauki.pl/articles/2047826.pdf
Data publikacji:
2007-10
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
42.25.Dd
72.15.Rn
Opis:
We present measurements of the spatial intensity distribution of localized modes in a two-dimensional open microwave cavity randomly filled with cylindrical dielectric scatterers. The robustness of these modes with respect to a modification of the boundaries of the scattering region is successfully established. From a comparison with numerically calculated modes, we can extract precise values of the localization length which are in agreement with the measured spectral widths. These results constitute unambiguous signatures of the existence of strongly localized electromagnetic modes in two-dimensional open random media.
Źródło:
Acta Physica Polonica A; 2007, 112, 4; 665-672
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł

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