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Tytuł:
Ultramarine, Lazurite and Sodalite Studied by Positron Annihilation and EPR Methods
Autorzy:
Baranowski, A.
Dębowska, M.
Jerie, K.
Jezierski, A.
Sachanbiński, M.
Powiązania:
https://bibliotekanauki.pl/articles/1933463.pdf
Data publikacji:
1995-07
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
71.60.+z
78.70.-g
61.90.+d
76.30.-v
Opis:
Studies of positron annihilation accompanied by EPR technique were undertaken for sodalite and lazurite and their synthetic counterparts (synthetic sodalite and ultramarines). Results of measurements performed by two techniques of positron annihilation spectroscopy (angular correlation of annihilation radiation, ACAR, and positron annihilation lifetime) revealed the undoubted influence of free radicals on positron annihilation mechanism but both inhibition of positronium formation by them and the effect of filling cages ought to be taken into account. The distinct differences between ACAR curves for sodalites, lazurites and ultramarines probably reflect the presence of different radicals in their cages and chemical heterogeneity as well as the disorder in Al, Si-site ordering in case of ultramarines. Comparison of the results of ACAR measurements with the ones of the EPR studies indicates that there is correspondence between them. Similarly to three families of the ACAR curves, different likes of EPR lines were obtained for three groups of samples; sodalites, lazurites and ultramarines. It is possible that the annihilation of positrons takes place mainly with unpaired electrons recorded by the EPR technique.
Źródło:
Acta Physica Polonica A; 1995, 88, 1; 29-41
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Transport and Magnetic Studies of New Mixed-Valence Compounds: K$\text{}_{3}$Cu$\text{}_{8}$Se$\text{}_{6}$, KCu$\text{}_{3}$Se$\text{}_{2}$, K$\text{}_{3}$Cu$\text{}_{8}$Te$\text{}_{6}$ and BaCuS$\text{}_{3-x}$
Autorzy:
Jacyna-Onyszkiewicz, I.
Sidowski, M.
Starodub, W.
Ratuszna, A.
Robaszkiewicz, S.
Powiązania:
https://bibliotekanauki.pl/articles/1955832.pdf
Data publikacji:
1997-02
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
75.20.-g
71.30.+h
Opis:
New mixed-valent copper chalcogenides BaCuS$\text{}_{3-x}$ and K$\text{}_{3}$Cu$\text{}_{8}$X$\text{}_{6}$ with X=Se or Te and KCu$\text{}_{3}$Se$\text{}_{2}$, with chemical patterns corresponding to the recently investigated K$\text{}_{3}$Cu$\text{}_{8}$S$\text{}_{6}$ and KCu$\text{}_{3}$S$\text{}_{2}$, were synthesized. For these new samples the results of resistivity and magnetic susceptibility measurements are presented. For BaCuS$\text{}_{3-x}$, K$\text{}_{3}$Cu$\text{}_{8}$Se$\text{}_{6}$ and KCu$\text{}_{3}$Se$\text{}_{2}$ the metal-insulator transition is observed with the low temperature phase being metallic, which is untypical, whereas K$\text{}_{3}$Cu$\text{}_{8}$Te$\text{}_{6}$ is a metal in the investigated temperature range. The temperature dependence of magnetic susceptibility of the studied samples testifies to their diamagnetic or weakly paramagnetic behaviour.
Źródło:
Acta Physica Polonica A; 1997, 91, 2; 405-408
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Thin Films Investigations by Means of Spin-Wave Resonance
Autorzy:
Maksymowicz, A. Z.
Maksymowicz, L. J.
Whiting, J. S. S.
Powiązania:
https://bibliotekanauki.pl/articles/1891792.pdf
Data publikacji:
1991-11
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
76.50.+g
76.30.-v
73.90.+f
Opis:
Magnetic resonance technique may successfully be applied to determine some basic parameters such as g-factor, magnetization M$\text{}_{s}$ or anisotropy energy constant K$\text{}_{u}$ in thin magnetic films. These parameters are obtained from a ferromagnetic resonance experiment when uniform precession of M$\text{}_{s}$ takes place. From spin-wave resonance one may extract very valuable information on the exchange constant A or the surface conditions characterized by the surface anisotropy energy (or pinning parameters ρ). In fact, it is only spin-wave resonance or similar techniques which allow for measurements of A, ρ or the coupling constant K$\text{}_{c}$ between ferromagnetic sublayers in multi-layered structure. The magnetic phase diagram, temperature dependence of the spin-waves stiffness constant, and the anisotropy energy constant may also be listed as less common examples of spin-wave resonance technique application for the investigation of thin films. This paper presents a theoretical approach to typical examples of experimental results and their interpretation from spin-wave resonance measurements.
Źródło:
Acta Physica Polonica A; 1991, 80, 5; 665-673
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Thermal Stability of Bent-Core Liquid Crystals Doped with Magnetic Nanoparticles
Autorzy:
Juríková, A.
Csach, K.
Miškuf, J.
Tomašovičová, N.
Mitróová, Z.
Závišová, V.
Koneracká, M.
Kopčanský, P.
Timko, M.
Éber, N.
Fodor-Csorba, K.
Vajda, A.
Powiązania:
https://bibliotekanauki.pl/articles/1387994.pdf
Data publikacji:
2015-02
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
61.30.-v
64.70.mj
65.80.-g
Opis:
In the work phase transitions in bent-core liquid crystals were studied using differential scanning calorimetry. For the binary mixture of bent-core molecules with 50 wt% of rod-shaped compound, the nematic to smectic transition occured below 40°C and the crystallization temperature shifted to sub-ambient temperatures. The influence of doping of the bent-core liquid crystals with magnetic nanoparticles on the kinetics of observed phase transitions was studied. The phase transition temperatures were shifted depending on the nanoparticle type and changed with varying cooling rate for all studied liquid crystal samples.
Źródło:
Acta Physica Polonica A; 2015, 127, 2; 638-640
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Theory of Nonlinear Ferromagnetic Resonance in the Samples with Magnetostatic and Exchange Boundary Conditions Imposed
Autorzy:
Krawiecki, A.
Sukiennicki, A.
Powiązania:
https://bibliotekanauki.pl/articles/1929206.pdf
Data publikacji:
1993-04
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
76.50.+g
75.30.Ds
75.70.-i
Opis:
General theory of nonlinear ferromagnetic resonance is presented for samples with the usual magnetostatic and exchange boundary conditions imposed at the sample surface. In such samples the Suhl instabilities and other nonlinear effects occur due to nonlinear interactions of magnetostatic or dipole-exchange modes. All relevant types of interactions are included in the Hamiltonian: with the pumping field, three- and four-mode ones. Analytic calculation of the Suhl thresholds in the three possible types of instabilities in perpendicular and parallel pumping is performed for the sample in the shape of a thin slab.
Źródło:
Acta Physica Polonica A; 1993, 83, 4; 505-515
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Theoretical and Experimental Analysis of Drying Various Geometrical Forms of Red Pepper
Autorzy:
Onat, A.
Binark, A.
Powiązania:
https://bibliotekanauki.pl/articles/1194108.pdf
Data publikacji:
2015-04
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
47.54.Bd
47.54.De
44.27.+g
44.30.+v
Opis:
In this study, a counter flow convection-type dryer was designed and manufactured. During experiments, four different geometrical forms of pepper specimens were dried in a complete (unsliced), perforated, crosscut, and longitudinally sliced forms. For each type of red pepper specimens, the experiments have been conducted at air velocity level of 0.5 m/s, relative humidity of 10-15%, and temperature of 55-60°C. The theoretical mathematical model of drying process was developed, considering the pepper's bottom surface to be isolated. The drying curves of experimental results are compared to ones obtained from the theoretical analyses. The comparison showed that experimental results are consistent with the theoretical model. The best results, considering the drying duration, are collected from the specimens sliced longitudinally, which were followed by the crosscut specimens, perforated and unsliced-complete specimens, respectively. 82% water (humidity) content in 500 g sample was reduced to 4% in longitudinally cut samples, 6% in crosscut samples, 7.5% in perforated samples and 8% in unsliced-complete samples, after 14 hours of drying. It is suggested that regarding to easiness of processing, the crosscut red peppers are more suitable, compared to the other geometrical forms.
Źródło:
Acta Physica Polonica A; 2015, 127, 4; 1388-1392
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Terahertz Detection of Quantum Cascade Laser Emission by Plasma Waves in Field Effect Transistors
Autorzy:
Teppe, F.
Consejo, C.
Torres, J.
Chenaud, B.
Solignac, P.
Fathololoumi, S.
Wasilewski, Z.
Zholudev, M.
Dyakonova, N.
Coquillat, D.
El Fatimy, A.
Buzatu, P.
Chaubet, C.
Knap, W.
Powiązania:
https://bibliotekanauki.pl/articles/1492959.pdf
Data publikacji:
2011-11
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
85.30.Tv
07.57.Kp
52.35.-g
Opis:
We report on the resonant detection of a 3.1 THz radiation produced by a quantum cascade laser using a 250 nm gate length GaAs/AlGaAs field effect transistor at liquid nitrogen temperature. We show that the physical mechanism of the detection is related to the plasma waves excited in the transistor channel. The detection is enhanced by increasing the drain current and driving the transistor into saturation regime. These results clearly show that plasma wave nanometer-size transistors can be used as detectors in all-solid-state terahertz systems where quantum cascade lasers act as sources.
Źródło:
Acta Physica Polonica A; 2011, 120, 5; 930-932
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Temperature Dependent Variations of Properties of Polymer-Like Carbon Coatings Treated with High Energy Electrons
Autorzy:
Plaipaitė-Nalivaiko, R.
Vigricaitė, L.
Adlienė, D.
Rutkūnienė, Ž.
Powiązania:
https://bibliotekanauki.pl/articles/1402232.pdf
Data publikacji:
2015-11
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
61.80.Fe
68.37.Ps
78.30.Jw
78.70.-g
Opis:
Polymer-like carbon coatings can be used for the protection of micro-electromechanical devices functioning in chemically or radiation harsh environment due to their beneficial properties. Properties of carbon coatings depend on the method of synthesis, initial gas mixture, admixture of additives, temperature and other technological parameters. Modification of carbon structures is possible applying high energy electrons. Coating mechanical properties become almost stable after their pretreatment with some doses of high energy electrons. Polymer-like carbon coatings were synthesized from acetylene gas plasma on n-type silicon substrates in the RF plasmotron system at temperatures in the range 293-673 K using plasma enhanced chemical vapor deposition method. Series of samples were prepared and irradiated with high energy (6 MeV) electrons in a medical linear accelerator. The ellipsometric method was used for estimation of some optical parameters and thickness of synthesized coatings. Structural changes of polymer-like carbon coatings were evaluated using the Raman spectroscopy and surface morphology was assessed by atomic force microscopy. Electron beam induced structural changes in the coatings were analyzed using the obtained results. The relations between the synthesis temperature and samples structure and surface morphology are discussed.
Źródło:
Acta Physica Polonica A; 2015, 128, 5; 915-917
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Temperature Dependence of Exchange Anisotropy of FeNi/FeMn Bilayers
Autorzy:
Żuberek, R.
Gutowski, M.
Szymczak, H.
Gnatchenko, S.
Merenkov, D.
Bludov, A.
Verkin, B.
Powiązania:
https://bibliotekanauki.pl/articles/1813596.pdf
Data publikacji:
2008-01
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
73.21.Ac
75.30.Et
75.70.-i
76.50.+g
Opis:
The influence of the bilinear and biquadratic coupling on the exchange anisotropy of the ferromagnetic/antiferromagnetic bilayer was studied by variable angle and temperature dependent ferromagnetic resonance. From the angular dependence of the resonance field the bilinear and biquadratic exchange coupling constants were determined.
Źródło:
Acta Physica Polonica A; 2008, 113, 1; 167-170
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Synchronization Among Spin-Wave Amplitudes in Chaotic Nonlinear Ferromagnetic Resonance
Autorzy:
Krawiecki, A.
Powiązania:
https://bibliotekanauki.pl/articles/2013977.pdf
Data publikacji:
2000-05
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
76.50.+g
75.30.Ds
05.45.+b
Opis:
A model of chaos in high-power ferromagnetic resonance in coincidence regime, based on three-magnon interactions of the uniform mode with a group of pairs of parametric spin waves, is investigated numerically. The results are interpreted from the point of view of chaotic synchronization theory. If all spin waves are identical, all of them are excited above the first-order Suhl instability threshold and in the chaotic regime their amplitudes show marginal synchronization, i.e. they differ only by a multiplicative factor, constant in time. If spin waves have slightly different instability thresholds, only one or few of them are excited. In the latter case, addition of weak thermal noise changes the results qualitatively. For low rf field amplitude, but above the threshold for chaos, still only few spin-wave pairs are excited above the thermal level. For higher rf field amplitude all spin waves in the group are excited, and their amplitudes are not synchronized. These results suggest that low correlation dimension of chaotic attractors, observed often in nonlinear ferromagnetic resonance, can be connected with chaotic synchronization among spin-wave amplitudes, in particular just above the threshold for chaos.
Źródło:
Acta Physica Polonica A; 2000, 97, 5; 947-950
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
SWR Studies of Higher-Order Surface Anisotropy Terms in (Ga,Mn)As Thin Films
Autorzy:
Puszkarski, H.
Tomczak, P.
Diep, H.
Powiązania:
https://bibliotekanauki.pl/articles/1030424.pdf
Data publikacji:
2018-03
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
75.50.Pp
76.50.+g
75.70.-i
75.30.Ds
76.60.-k
Opis:
We extend the theory of spin-wave resonance (SWR) by introducing a new formula representing the surface pinning parameter as a series of contributions from different anisotropies existing in (Ga,Mn)As thin films. Comparing our theory with the reported experimental studies of SWR in thin films of the ferromagnetic semiconductor (Ga,Mn)As, we find that besides the first-order cubic anisotropy, higher-order cubic anisotropies (in the second and third orders) as well as uniaxial anisotropies (perpendicular in the first and second orders, and in-plane diagonal) occur on the surface of this material. To our best knowledge this is the first report of the existence of higher-order surface anisotropy fields in (Ga,Mn)As thin films.
Źródło:
Acta Physica Polonica A; 2018, 133, 3; 635-638
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Superparamagnetic-Like Behaviour in RE$\text{}_{2}$WO$\text{}_{6}$ Tungstates (Where RE = Nd, Sm, Eu, Gd, Dy, Ho and Er)
Autorzy:
Groń, T.
Tomaszewicz, E.
Urbanowicz, P.
Duda, H.
Mydlarz, T.
Powiązania:
https://bibliotekanauki.pl/articles/2048133.pdf
Data publikacji:
2011-05
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
75.20.-g
75.25.Dk
75.30.Cr
73.61.Ng
Opis:
The magnetization isotherms were used to study the superparamagnetic-like behaviour in polycrystalline (powder) RE$\text{}_{2}$WO$\text{}_{6}$ tungstates (where RE = Nd, Sm, Eu, Gd, Dy, Ho and Er). The magnetization isotherms of the majority tungstates under study revealed both the spontaneous magnetic moments and hysteresis characteristic for the superparamagnetic-like behaviour with blocking temperature T$\text{}_{B}$ ≈ 30 K except the Sm$\text{}_{2}$WO$\text{}_{6}$ and Eu$\text{}_{2}$WO$\text{}_{6}$ compounds.
Źródło:
Acta Physica Polonica A; 2011, 119, 5; 708-710
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Structure of Free Radical inγ-Irradiated 21-Hydroxyprogesterone (Deoxycorticosterone) Single Crystals. ESR/ENDOR and DFT Studies
Autorzy:
Szyczewski, A.
Pietrzak, J.
Möbius, K.
Powiązania:
https://bibliotekanauki.pl/articles/2043407.pdf
Data publikacji:
2005-07
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
76.30.-v
76.70.-r
78.70.-g
31.15.Ew
Opis:
Single crystals of 21-hydroxyprogesterone have been γ-irradiated at 295 K and studied using X-band ESR and ENDOR. The structure of the one type radical has been determined on the basis of an analysis of the angular variation of the spectra. This radical is formed by abstraction of the hydrogen atom from the C(6) carbon, while the unpaired electron is delocalised onto the system O(3), C(3), C(4), C(5), C(6). Hyperfine splitting constants and unpaired electron density distribution have been calculated for the proposed radical structure by using the Gaussian98 set of programs. The results are in very good agreement with the experimental data. The effect of the hydrogen bond and biological activity on the anisotropy of α-hyperfine splitting tensor have also been discussed.
Źródło:
Acta Physica Polonica A; 2005, 108, 1; 119-126
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Structural Stochastic Multiresonance in Hierarchical Networks
Autorzy:
Krawiecki, A.
Kaim, M.
Powiązania:
https://bibliotekanauki.pl/articles/1409029.pdf
Data publikacji:
2012-02
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
05.45.-a
75.30.Ds
76.50.+g
Opis:
Systems with a structure of hierarchical networks, consisting of simple units placed in the nodes and interacting along the edges of the network, are ubiquitous in the modern society and economy. In this paper the problem of signal detection and transmission in such systems in the presence of noise is analyzed from the point of view of stochastic resonance. As examples simple tree-like and more complex Ravasz-Barabási networks of interacting threshold elements are considered. It is shown that stochastic multiresonance is often observed, a phenomenon characterized by the presence of two or more maxima of the output signal-to-noise ratio as a function of the input noise intensity. The origin of the additional maxima, which occur for small noise intensities, can be related to the structure of the interactions, thus the observed phenomenon is an example of structural stochastic multiresonance.
Źródło:
Acta Physica Polonica A; 2012, 121, 2B; B-72-B-76
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Some Properties of the Model of a~Superconductor with Pair Hopping and Magnetic Interactions at Half-Filling
Autorzy:
Kapcia, K.
Powiązania:
https://bibliotekanauki.pl/articles/1431185.pdf
Data publikacji:
2012-04
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
71.10.Fd
71.10.-w
74.20.-z
74.81.-g
75.30.Fv
Opis:
We present our preliminary studies of an effective model of a superconductor with short coherence length involving magnetic interactions. The Hamiltonian considered consists of (i) the effective on-site interaction U, (ii) the intersite magnetic exchange interactions ($J^z,$ $J^{xy}$) between nearest-neighbors and (iii) the intersite charge exchange term I, determining the hopping of electron pairs between nearest-neighbor sites. In the analysis of the phase diagrams and thermodynamic properties of this model for half-filling (n=1) we have adopted the variational approach, which treats the on-site interaction term exactly and the intersite interactions within the mean-field approximation. One finds that the system considered can exhibit very interesting multicritical behaviors (including tricritical, critical-end and bicritical points) caused by the competition between magnetism and superconductivity, even for n=1. Our investigations show that, depending on the values of interaction parameters, the system at half-filling can exhibit three homogeneous phases: superconducting (SS), (anti-)ferromagnetic (F) and nonordered (NO). The transitions between ordered phases (SS, F) and the NO phase can be first order as well as second order ones, whereas SS-F transition is first order one. Temperature dependencies of the order parameters and thermodynamic properties of the system at the sequence of transitions: SS→F→NO with increasing temperature for J/I=0.3, U/I_0 = 0.69 and n=1 are also presented.
Źródło:
Acta Physica Polonica A; 2012, 121, 4; 733-737
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł

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