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Wyszukujesz frazę "Čižmar, E." wg kryterium: Autor


Tytuł:
Magnetocaloric Effect in NiCl₂(bipy) at Low Temperatures
Autorzy:
Ráczová, K.
Čižmár, E.
Feher, A.
Powiązania:
https://bibliotekanauki.pl/articles/1032298.pdf
Data publikacji:
2017-04
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
75.30.Sg
75.30.Gw
75.10.Pq
Opis:
Magnetothermal properties of the compound NiCl₂(bipy), where bipy = 4,4'-bipyridine, were studied. The single-ion anisotropy of Ni(II) ions was estimated and its influence on magnetocaloric effect in NiCl₂(bipy) was investigated. Above the metamagnetic transition a maximum in the isothermal change of the magnetic entropy is reached near 11 K at field change from 0T to 7T with peak value -ΔS = 6J K¯¹ kg¯¹. The temperature dependence of ΔS above 7K agrees with the assumed easy-axis type of single-ion anisotropy. The inverse magnetocaloric effect, typical for ordered antiferromagnets, was observed in the ordered state of NiCl₂(bipy) only for isothermal magnetization in small fields up to 2T.
Źródło:
Acta Physica Polonica A; 2017, 131, 4; 922-924
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
EPR Spectra of the Genuine-Organic and Metal-Organic TCNQ-Based Anion Radical Salts
Autorzy:
Botko, M.
Čižmár, E.
Kajňaková, M.
Feher, A.
Powiązania:
https://bibliotekanauki.pl/articles/1368637.pdf
Data publikacji:
2014-07
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
75.50.Xx
76.30.-v
Opis:
We have measured the electron paramagnetic resonance spectra of genuine-organic anion-radical salts $[Me-2,6-di-Me-Py](TCNQ)_{2}$, $[Me-3,5-di-Me-Py](TCNQ)_{2}$, $[N-Me-OH-Me-Py](TCNQ)_{2}$, $[N-Et-OH-Me-Py](TCNQ)_{2}$, and metal-organic anion-radical salt $[Mn-phen_{3}](TCNQ)_{2}$·$H_{2}O$ in the temperature range from 2 K to 300 K in the X-band frequency range. A comparison study of the shape of spectra, g-factors and linewidths with respect to the composition and crystal structure of studied compounds is presented. While the genuine-organic anion-radical salts display a typical EPR response originating from TCNQ pairs, the spectra of metal-organic anion-radical salt are dominated by the contribution of transition metal.
Źródło:
Acta Physica Polonica A; 2014, 126, 1; 252-253
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
The magnetocaloric effect in {[Cu(bapa)]₃[Cr(CN)₆]₂}ₙ · 6n H₂O at low temperatures
Autorzy:
Ráczová, K.
Vavra, M.
Hegedüs, M.
Čižmár, E.
Powiązania:
https://bibliotekanauki.pl/articles/1048121.pdf
Data publikacji:
2018-03
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
75.30.Sg
75.30.Gw
75.10.Pq
Opis:
The crystals of {[Cu(bapa)]₃[Cr(CN)₆]₂}ₙ·6nH₂O (bapa = bis(3-aminopropyl)amine) are formed by infinite Cu(II)-Cr(III) antiparallel chains, which are connected into the third direction by additive [Cu(bapa)] moieties. The onset of long-range magnetic order at 3.2 K was observed by AC susceptibility. The study of the magnetocaloric effect from magnetization measurements yields a large entropy change -ΔS_{M} = 13.65 J K¯¹mol¯¹ (-ΔS_{M} = 12.25 J kg¯¹K¯¹) at the field change from 0 T to 3 T at temperature 4 K. The analysis of the critical behavior of -ΔS_{M} suggests the value of critical exponent n = 0.577 at the ordering temperature characteristic for three-dimensional magnets with Ising anisotropy.
Źródło:
Acta Physica Polonica A; 2018, 133, 3; 429-431
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Magnetic specific heat of anion-radical salt [Ni(bipy)₃](TCNQ)₄·(CH₃)₂CO at very low temperatures
Autorzy:
Šoltésová, D.
Čižmár, E.
Vasylets, G.
Starodub, V.
Feher, A.
Powiązania:
https://bibliotekanauki.pl/articles/1053060.pdf
Data publikacji:
2017-04
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
65.40.Ba
75.30.Et
75.30.Gw
Opis:
Thermodynamic studies of the anion-radical salt system [Ni(bipy)₃](TCNQ)₄·(CH₃)₂CO, where TCNQ is 7,7',8,8'-tetracyano-quinodimethane, are reported. The anion-radical salt systems based on TCNQ belong to a material class in which the arrangement of the anion-radical salt has considerable impact on the charge transfer and magnetic properties. The crystal structure of the studied compound consists of [Ni(bipy)₃]⁺² cations containing Ni⁺² ions and four types of crystallographically independent anion-radicals TCNQ^{·-} (A, B, C and D). These TCNQ^{·-} radicals form two different types of TCNQ^{·-} stacks (AABB and CCDD), where a strong exchange interaction is expected. The temperature dependence of the specific heat of a single crystal was studied in magnetic fields up to 5 T and in the temperature range from 0.4 K to 30 K. The temperature dependence of specific heat displays a broad Schottky-like maximum above 0.4 K. Using a single-ion approximation, the analysis of the temperature dependence of the specific heat below 10 K yields values for the anisotropy parameters, D/k_{B}=-1.95 K and E/k_{B}=0.3 K. These results suggest that the observed maximum in the specific heat originates from Ni⁺² ions while the exchange interaction between the transition metal ions and the TCNQ is negligible.
Źródło:
Acta Physica Polonica A; 2017, 131, 4; 925-927
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Observation of Anisotropic Exchange in a Spin Ladder by ESR
Autorzy:
Čižmár, E.
Ozerov, M.
Krämer, K.
Rüegg, Ch.
Zvyagin, S.
Powiązania:
https://bibliotekanauki.pl/articles/1368577.pdf
Data publikacji:
2014-07
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
76.30.-v
74.25.Ha
75.50.Gg
75.30.Gw
Opis:
We report on high resolution X-band electron spin resonance (ESR) spectroscopy studies of the spin-ladder material $(C_{5}H_{12}N)_{2}CuBr_{4}$. Our experiments provide a direct evidence for the presence of anisotropy in $(C_{5}H_{12}N)_{2}CuBr_{4}$ in contrast to a fully isotropic spin-ladder model employed for this system previously. Low-temperature angular dependence of ESR transitions is analyzed employing a simple spin-1/2 dimer model with the symmetric anisotropic exchange interaction.
Źródło:
Acta Physica Polonica A; 2014, 126, 1; 238-239
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Spin Glass State in S=3/2 Kagomé Antiferromagnet $Co(N_{3})_{2}(bpg)[(CH_{3})_{2}(NCOH)]_{4/3}$
Autorzy:
Vrábel, P.
Čižmár, E.
Orendáčová, A.
Gao, S.
Orendáč, M.
Powiązania:
https://bibliotekanauki.pl/articles/1368680.pdf
Data publikacji:
2014-07
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
75.50.Ee
75.30.Et
75.10.Nr
Opis:
Specific heat, magnetic susceptibility and magnetization of $Co(N_{3})_{2}(bpg)[(CH_{3})_{2}(NCOH)]_{4/3}$, representing S=3/2 kagomé system are reported. Long-range ordering at 16 K was revealed, however, at lower temperatures slow spin dynamics is still found. The analysis of alternating susceptibility suggests the onset of glassy state. The study of the time dependence of magnetization revealed the existence of more relaxation channels with pronounced different relaxation times. The observed behaviour is consistent with the formation of topological spin glass in which relaxation is governed by both spin and chiral degrees of freedom.
Źródło:
Acta Physica Polonica A; 2014, 126, 1; 266-267
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Experimental Studies of S=1 Heisenberg Planar Antiferromagnetic Chain Ni(C$\text{}_{11}$H$\text{}_{10}$N$\text{}_{2}$O)$\text{}_{2}$Ni(CN)$\text{}_{4}$
Autorzy:
Čizmár, E.
Černák, J.
Orendáč, M.
Herrmannsdörfer, T.
Feher, A.
Powiązania:
https://bibliotekanauki.pl/articles/2013230.pdf
Data publikacji:
2000-03
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
75.40.Cx
71.20.Be
75.50.Ee
Opis:
In this paper we discuss the results of experimental studies of specific heat and magnetic susceptibility of chain compound Ni(C$\text{}_{11}$H$\text{}_{10}$N$\text{}_{2}$O)$\text{}_{2}$Ni(CN)$\text{}_{4}$. We have observed a Schottky type anomaly at T=2.2 K in a temperature dependence of specific heat and the compound was identified as a S=1 Heisenberg antiferromagnetic chain with the subcritical exchange coupling D/k$\text{}_{B}$=5 K, D/|J|=5.2 and the strong in-plane anisotropy E/k$\text{}_{B}$=2.8 K. It has been found that the in-plane anisotropy affects the region of validity of a diluted exciton model [1] and a strong coupling model [2] for S=1 Heisenberg chains with the strong planar anisotropy. The analysis suggests that the in-plane anisotropy should be considered in any attempt to find a compound potentially located in the boundary of Haldane and "large-D" phases.
Źródło:
Acta Physica Polonica A; 2000, 97, 3; 579-582
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Spin-Peierls Transition in $(N-Me-Tetra-Me-Pz)(TCNQ)_{2}$
Autorzy:
Kajňaková, M.
Botko, M.
Starodub, V.
Čižmár, E.
Feher, A.
Powiązania:
https://bibliotekanauki.pl/articles/1368650.pdf
Data publikacji:
2014-07
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
64.60.i
75.10.Jm
75.50.Xx
76.30.v
Opis:
The new organic anion-radical salt $(N-Me-Tetra-Me-Pz)(TCNQ)_{2}$, (Pz = pyrazine) was studied as a low dimensional magnetic system. Heat capacity and EPR studies were performed in the temperature range from 2 to 300 K. The magnetic susceptibility was measured in the temperature range from 2 to 300 K and in magnetic fields of 100 mT and 1 T. The magnetic properties of this new system can be described as a dimerized Heisenberg spin S=1/2 chain possessing a spin-Peierls transition at 42 K.
Źródło:
Acta Physica Polonica A; 2014, 126, 1; 254-255
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Experimental Study of the Magnetocaloric Effect in Ni(en)(H₂O)₄SO₄·2H₂O - An S = 1 Molecular Magnet with Easy-Plane Anisotropy
Autorzy:
Tarasenko, R.
Orendáčová, A.
Čižmár, E.
Orendáč, M.
Potočňák, I.
Feher, A.
Powiązania:
https://bibliotekanauki.pl/articles/1032138.pdf
Data publikacji:
2017-04
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
75.30.Sg
75.30.Gw
71.70.Ch
Opis:
Magnetocaloric properties of Ni(en)(H₂O)₄SO₄·2H₂O powder were investigated in temperature range from 2 K to 30 K in magnetic fields up to 7 T using isothermal magnetization measurements. The maximum value of the isothermal entropy change in the field 7 T is about 8 J/(kg K), with a refrigerant capacity of 55 J/kg. Temperature dependence of the isothermal entropy change under different magnetic fields is in good agreement with theoretical predictions from crystal electric field parameters.
Źródło:
Acta Physica Polonica A; 2017, 131, 4; 904-906
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Application of Superconductor/Photosemiconductor Contact Structures in Electronics
Autorzy:
Bunda, V.
Bunda, S.
Komanicky, V.
Botko, M.
Čižmár, E.
Feher, A.
Powiązania:
https://bibliotekanauki.pl/articles/1202071.pdf
Data publikacji:
2014-07
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
74.45.+c
74.78.-w
85.25.Hv
Opis:
In recent years, two-dimensional (2D) nanostructured materials, such as nanoplates and nanosheets, have attracted much attention because of their unique electronic, magnetic, optical, and catalytic properties, which mainly arise from their large surface areas, nearly perfect crystallinity, structural anisotropy, and quantum confinement effects in the thickness. The 2D nanostructured materials can be used as building blocks for advanced materials and devices with designed functions in areas as diverse, as lasers, transistors, catalysis, solar cells, light emission diodes, chemical and biological sensors. We report physical properties of YBCO/BiOI contact structures and electrophysical properties of BiOI single crystal.
Źródło:
Acta Physica Polonica A; 2014, 126, 1; 362-363
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
EPR Study of the Two-Dimensional Quantum System $Cu(en)(H_2O)_2SO_4$
Autorzy:
Tarasenko, R.
Orendáčová, A.
Čižmár, E.
Orendáč, M.
Zvyagin, S.
Wosnitza, J.
Powiązania:
https://bibliotekanauki.pl/articles/1427109.pdf
Data publikacji:
2012-05
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
76.30.Fc
75.40.-s
Opis:
The angular dependence of electron paramagnetic resonance spectra of $Cu(en)(H_2O)_2SO_4$ single crystals was studied in the X-band frequency range at temperatures 4 and 300 K. Analysis of the linewidth at 300 K revealed nice agreement with the angular variation of the g-factor. This coincidence is the manifestation of the symmetric and antisymmetric exchange coupling, as main broadening mechanisms in $Cu(en)(H_2O)_2SO_4$ at high temperatures. The radical change of the angular dependence of the linewidth observed at 4 K can be ascribed to dipolar coupling.
Źródło:
Acta Physica Polonica A; 2012, 121, 5-6; 1095-1097
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Frustrated zig-zag spin chains formed by hydrogen bonds in [Cu(H₂O)(OH)(tmen)]₂[Pd(CN)₄]·2H₂O
Autorzy:
Čižmár, E.
Orendáčová, A.
Orendáč, M.
Kuchár, J.
Feher, A.
Park, J.
Meisel, M.
Powiązania:
https://bibliotekanauki.pl/articles/1054768.pdf
Data publikacji:
2017-04
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
75.30.Et
76.30.-v
75.40.-s
Opis:
The magnetic properties of the novel dimeric compound [Cu(H₂O)(OH)(tmen)]₂[Pd(CN)₄]·2H₂O (tmen=N,N,N',N'-tetramethylethylenediamine) with modulated crystal structure were studied in the temperature range from 95 mK to 300 K. Magnetic measurements revealed a presence of weak antiferromagnetic exchange coupling in the compound. The temperature dependence of specific heat is characterized by the presence of a Schottky-like maximum at 0.47 K and a λ-anomaly at 0.28 K, indicating the formation of long-range order in the system. The comparison of the experimental data with theoretical predictions revealed the presence of antiferromagnetic intradimer exchange coupling J/k_{B}= -1.2 K and interdimer coupling of a similar strength mediated via hydrogen bonds between dimeric units forming a frustrated magnetic zig-zag chain structure.
Źródło:
Acta Physica Polonica A; 2017, 131, 4; 940-942
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Growth of Pt-Ni nanoparticles of different composition using electrodeposition and characterization of their magnetic properties
Autorzy:
Kožejová, M.
Hložná, D.
Hua Liu, Y.
Ráczová, K.
Čižmár, E.
Orendáč, M.
Komanický, V.
Powiązania:
https://bibliotekanauki.pl/articles/1053087.pdf
Data publikacji:
2017-04
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
75.75.+a
75.75.Fk
82.45.Qr
68.37.Hk
Opis:
We prepared Pt₃Ni and PtNi₃ nanoparticles of various sizes on conductive and atomically smooth highly oriented pyrolytic graphite surfaces using potentiostatic electrodeposition. We can control the size of electrodeposited nanoparticles and their density on the surface by changing the deposition time. The morphology of nanoparticles was determined by scanning electron microscopy. PtNi₃ particles have spherical shape, while Pt₃Ni particles have more irregular shape. Composition of particles was confirmed by energy dispersive spectroscopy. We have measured magnetic properties of both systems with 100 s preparation time, superparamagnetic behavior was observed in PtNi₃ nanoparticles with blocking temperature T_{B}=225 K.
Źródło:
Acta Physica Polonica A; 2017, 131, 4; 839-841
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Magnetic Properties of an S=2 Ladder Spin Model Applied to a New Quasi-One-Dimensional Magnet $[Mn(phen)_{3}](TCNQ)_{2}·H_{2}O$
Autorzy:
Botko, M.
Cheranovskii, V.
Vasilets, G.
Čižmar, E.
Kajňaková, M.
Anders, A.
Starodub, V.
Feher, A.
Powiązania:
https://bibliotekanauki.pl/articles/1366461.pdf
Data publikacji:
2014-07
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
75.50.Xx
75.10.Jm
76.10.Pq
Opis:
The effective spin S=2 Heisenberg ladder model with free-spin admixtures was proposed for the study of the low-temperature magnetic properties of the complex compound $[Mn(phen)_{3}](TCNQ)_{2}·H_{2}O$. The temperature dependence of magnetic susceptibility was found to be close to experimental data.
Źródło:
Acta Physica Polonica A; 2014, 126, 1; 20-21
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
$CuBr_2(C_{10}H_8N_2) - S = 1//2$ Two-Dimensional Rectangular Heisenberg Antiferromagnet
Autorzy:
Čižmár, E.
Kajňaková, M.
Orendáčová, A.
Orendáč, M.
Feher, A.
Anders, A.
Park, J.
Meisel, M.
Powiązania:
https://bibliotekanauki.pl/articles/1534990.pdf
Data publikacji:
2010-11
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
75.30.Et
75.50.Ee
76.30.-v
Opis:
Magnetic susceptibility and X-band electron spin resonance study of a two-dimensional Heisenberg antiferromagnetic system $CuBr_2$(bipy), where bipy = $C_{10}H_8N_2$ is 4,4'-bipyridyl, has been performed in the temperature range from 300 K down to 2 K. A rhombic anisotropy of the g-factor was obtained from X-band EPR measurements with $g_{x}$ = 2.037, $g_{y}$ = 2.100 and $g_{z}$ = 2.219. The temperature dependence of the magnetic susceptibility with a round maximum observed at 28 K suggests antiferromagnetic type of short-range order. No signature of the magnetic long-range order in studied compound was observed. The comparison of the magnetic susceptibility data with a two-dimensional rectangular Heisenberg model yields the values of intralayer exchange couplings J/$k_{B}$ = - 47 K and J'/$k_{B}$ = - 9.4 K.
Źródło:
Acta Physica Polonica A; 2010, 118, 5; 973-974
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł

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