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Wyszukujesz frazę "Sechovský, V." wg kryterium: Autor


Tytuł:
Magnetic Phase Transitions and Thermal Properties of $Ho(Co_{1-x}Si_x)_2$ Compounds
Autorzy:
Vasylyev, D.
Prokleška, J.
Sechovský, V.
Powiązania:
https://bibliotekanauki.pl/articles/1813682.pdf
Data publikacji:
2008-01
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
75.30.Sg
75.50.Gg
Opis:
The specific heat of $HoCo_2$ and $Ho(Co_{0.95}Si_{0.05})_2$ was measured as a function of temperature in several constant magnetic fields up to 8 T. A data analysis allowed us to determine the isothermal entropy change and the magnetocaloric effect in a wide temperature range. The considerable values of the magnetocaloric effect in the vicinity of the magnetic ordering transition are qualifying both compounds as suitable for magnetic refrigeration purposes. The magnetic phase transition temperature $(T_C)$ increases from 77 K for $HoCo_2$ to 103 K for $Ho(Co_{0.95}Si_{0.05})_2$ while the large magnetocaloric effect in the vicinity of TC is maintained, which demonstrates possible ways of tuning the operating temperatures of the magnetic refrigerant.
Źródło:
Acta Physica Polonica A; 2008, 113, 1; 347-350
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Magnetism in $UCo_{0.88}Ru_{0.12}Ge$ Studied by Polarized Neutrons
Autorzy:
Vališka, M.
Pospíšil, J.
Nénert, G.
Stunault, A.
Prokeš, K.
Sechovský, V.
Powiązania:
https://bibliotekanauki.pl/articles/1371426.pdf
Data publikacji:
2014-07
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
74.70.Tx
61.05.fm
75.25.-j
Opis:
UCoGe is an archetype of coexisting weak itinerant 5f-electron ferromagnetism ($T_{C}$~3 K, $μ_{s}$=$0.03μ_{B}$/f.u.) and superconductivity ($T_{SC}$~ 0.6 K) at ambient pressure. The Ru substitution for Co leads to an initial sharp increase of the $T_{C}$ up to the maximum of $T_{C}$=8.5 K for x=0.12, increase of spontaneous magnetic moment and suppression of superconductivity. We have grown the $UCo_{0.88}Ru_{0.12}Ge$ single crystal and studied magnetization along the principal crystallographic axes. To see the microscopic background of these findings we performed a polarized neutron diffraction experiment on D3 diffractometer in ILL. We have found that the Co and U moments are parallel in $UCo_{0.88}Ru_{0.12}Ge$, in contrast to the antiparallel configuration in UCoGe. This is probably the reason of the spontaneous magnetization increase with Ru doping.
Źródło:
Acta Physica Polonica A; 2014, 126, 1; 330-331
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Presence of Parimagnetism in $Ho(Co_{1-x}Si_{x})_{2}$ Under Hydrostatic Pressure
Autorzy:
Valenta, J.
Prchal, J.
Kratochvílová, M.
Míšek, M.
Sechovský, V.
Powiązania:
https://bibliotekanauki.pl/articles/1372511.pdf
Data publikacji:
2014-07
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
75.20.En
75.50.Gg
Opis:
A new configuration of cobalt magnetic moments with respect to rare-earth ones on local level, named as parimagnetism, surviving above the Curie temperature was determined few years ago for $ErCo_{2}$. Occurrence of parimagnetism has recently been confirmed also for $HoCo_{2}$. In this paper we present results manifesting considerable composition and hydrostatic-pressure influence on characteristic temperatures of magnetism in $Ho(Co_{1-x}Si_{x})_{2}$ compounds and draw a preliminary scenario analyzing the exchange interactions involved.
Źródło:
Acta Physica Polonica A; 2014, 126, 1; 406-408
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Scattering of Phonons in $CsMnCl_3 \cdot 2H_2O$
Autorzy:
Tkáč, V.
Tibenská, K.
Orendáčová, A.
Orendáč, M.
Šebek, J.
Sechovský, V.
Anders, A.
Feher, A.
Powiązania:
https://bibliotekanauki.pl/articles/1534857.pdf
Data publikacji:
2010-11
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
75.30.Et
75.40.Cx
66.70.Lm
75.30.Ds
Opis:
The thermal conductivity of the quasi-one-dimensional S = 5/2 Heisenberg antiferromagnet $CsMnCl_3 \cdot 2H_2O$ with the intrachain interaction $J//k_{B}$ = 3 K was experimentally studied at temperatures from 2 to 25 K. The data analysis performed within the Debye model with the relaxation-time approximation unambiguously indicates the presence of the scattering of phonons on magnetic subsystem.
Źródło:
Acta Physica Polonica A; 2010, 118, 5; 950-952
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Thermal Conductivity of a Layered $CsGd(MoO_4)_2$ Crystal
Autorzy:
Tibenská, K.
Tkáč, V.
Orendáčová, A.
Orendáč, M.
Feher, A.
Šebek, J.
Sechovský, V.
Powiązania:
https://bibliotekanauki.pl/articles/1534983.pdf
Data publikacji:
2010-11
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
75.30.Et
75.40.Cx
66.70.Lm
75.30.Ds
Opis:
The thermal conductivity of $CsGd(MoO_4)_2$ has been studied in the temperature range from 2 to 50 K in zero magnetic field. The analysis of the data performed within the Debye model with the relaxation-time approximation revealed the presence of the scattering of phonons by critical fluctuations. The behaviour of phonon mean free path at the lowest temperatures is discussed.
Źródło:
Acta Physica Polonica A; 2010, 118, 5; 971-972
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Magnetocaloric effect in CsDy(MoO₄)₂
Autorzy:
Tarasenko, R.
Tkáč, V.
Orendáčová, A.
Orendáč, M.
Sechovský, V.
Feher, A.
Powiązania:
https://bibliotekanauki.pl/articles/1050647.pdf
Data publikacji:
2018-03
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
75.30.Sg
75.30.Gw
71.70.Ej
Opis:
CsDy(MoO₄)₂ belongs to the family of binary alkaline rare-earth molybdates, with detectable low-temperature structural phase transitions, caused by the cooperative Jahn-Teller effect. Magnetocaloric studies of a single crystal of CsDy(MoO₄)₂ have been performed in the temperature range from 2 K to 18 K in magnetic fields up to 7 T applied along the crystallographic a axis. The maximum value of the isothermal entropy change is about 8 J/(kgK) and was achieved already in the fields above 2 T. The observed results suggest that the studied system can be used as a magnetic refrigerant at helium temperatures.
Źródło:
Acta Physica Polonica A; 2018, 133, 3; 414-416
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Magnetism in TmCo₂
Autorzy:
Šebesta, J.
Prchal, J.
Valenta, J.
Kratochvílová, M.
Sechovský, V.
Powiązania:
https://bibliotekanauki.pl/articles/1385702.pdf
Data publikacji:
2015-02
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
75.20.En
75.50.Gg
71.70.Gm
Opis:
Recently a new wave of interest in physics of RCo₂ compounds has been boosted by reports on unusual magnetic short range order configurations in the heavy rare-earth RCo₂ ferrimagnets in paramagnetic state. The newly observed phenomenon called parimagnetism consists in a short-range antiferromagnetic coupling between small ferromagnetic Co clusters and the nearest rare-earth moments. This paper is devoted to results of our experimental investigation of carefully prepared and characterized samples of TmCo₂, a compound on which controversial results can be found in literature. Detailed magnetization, AC susceptibility, specific heat and electrical resistivity measurements revealed two magnetic phase transitions at 4.6 and 3.6 K, respectively. The anomalies connected with the transitions are strongly dependent on magnetic field and hydrostatic pressure. The AC susceptibility anomaly connected with the onset of parimagnetism has been found at $T_{f}$=35 K. Contrary to other heavy rare-earth RCo₂ counterparts $T_{f}$ of TmCo₂ is entirely pressure independent.
Źródło:
Acta Physica Polonica A; 2015, 127, 2; 379-381
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Magnetic Structure in UIrAl
Autorzy:
Prokeš, K.
Prchal, J.
Sechovský, V.
Andreev, A.
Powiązania:
https://bibliotekanauki.pl/articles/1813678.pdf
Data publikacji:
2008-01
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
75.25.+z
Opis:
By means of neutron diffraction on a hexagonal UIrAl single crystal we find that this system orders ferromagnetically at low temperatures with magnetic moments of 0.93 (10) $μ_B$ aligned along the c axis. The Curie temperature $T_C$ = 65 (5) K determined from the diffraction experiment is in good agreement with bulk magnetic measurements.
Źródło:
Acta Physica Polonica A; 2008, 113, 1; 339-342
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Magnetism in $RCo_{2}$ (R = Dy, Ho, Er, Tm) Under Hydrostatic Pressure
Autorzy:
Prchal, J.
Šebesta, J.
Valenta, J.
Míšek, M.
Turčinková, D.
Lapčák, L.
Prokleška, J.
Kratochvílová, M.
Sechovský, V.
Powiązania:
https://bibliotekanauki.pl/articles/1369111.pdf
Data publikacji:
2014-07
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
75.20.En
75.50.Gg
Opis:
The short-range parimagnetic configurations, observed in the heavy rare-earth $RCo_{2}$ compounds in paramagnetic range far above the Curie temperature $T_{C}$, consist in formation of ferromagnetic cobalt clusters antiferromagnetically coupled to the neighboring R magnetic moments. The characteristic temperature of the onset of parimagnetism $T_{f}$ is very sensitive to changes of external conditions like pressure or composition. The pressure coefficients $∂T_{f}$/∂p and $∂T_{C}$/∂p are comparable, indicating a close connection of underlying mechanisms. Our recent measurements indicate systematic evolution of the pressure coefficients with spanning the rare-earth series from Dy through Tm in $RCo_{2}$ with a specific case $TmCo_{2}$.
Źródło:
Acta Physica Polonica A; 2014, 126, 1; 288-289
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Magnetic Properties of a Novel $CeCo_{0.715}Si_{2.285}$ Compound
Autorzy:
Moudřík, J.
Prokleška, J.
Pospíšil, J.
Sechovský, V.
Císařová, I.
Powiązania:
https://bibliotekanauki.pl/articles/1387062.pdf
Data publikacji:
2015-02
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
75.30.-m
75.30.Gw
75.30.Kz
Opis:
We report on the basic physical properties of a novel $CeCo_{0.715}Si_{2.285}$ compound, mainly its rich magnetic phase diagram. The compound crystallizes in the I-4m2 space group structure with extremely elongated unit cell (a = 4.12 Å, c = 32.84 Å). In a zero magnetic field it orders antiferromagnetically at $T_{N}$ = 10.5 K with another order-to-order transition at 9.5 K. Under application of a magnetic field along the c-axis it manifests numerous magnetic transitions in small fields (B < 500 mT), resembling the so-called "devil's staircase" systems. Above 1 T the magnetization is almost constant up to 14 T (maximum magnetic field applied within our study) but considerably reduced (0.3 $μ_B$/Ce) with respect to the free $Ce^{3+}$ ion. After removing the applied field, however, the high field state remains unchanged to be removed in negative fields. The compound also exhibits strong hysteresis of magnetization with respect to varying temperature or magnetic field. For fields applied along the a-axis typical behavior for the hard axis in the material with uniaxial anisotropy is observed.
Źródło:
Acta Physica Polonica A; 2015, 127, 2; 561-563
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Solution Growth and Investigation of the Single Crystals from the CePdIn System
Autorzy:
Kratochvílová, M.
Custers, J.
Sechovský, V.
Powiązania:
https://bibliotekanauki.pl/articles/1371341.pdf
Data publikacji:
2014-07
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
81.10.Dn
68.37.Hk
65.40.Ba
75.30.Mb
Opis:
We report on the investigation of recently discovered heavy fermion compounds within the Ce-Pd-In system. Single crystals of $Ce_{n}Pd_{m}In_{3n+2m}$ (n=2, 3, 5; m=1, 2) and $Ce_{4}Pd_{10}In_{21}$ were synthesized from In-flux. Specific heat measurements of the multiphase $Ce_{n}Pd_{m}In_{3n+2m}$ system revealed a superconducting transition at $T_{c}$=0.69 K arising from $Ce_{2}PdIn_{8}$ and another, magnetic transition at $T_{m}$=1.67 K arising from either $Ce_{3}PdIn_{11}$ or $Ce_{5}Pd_{2}In_{19}$. Low-temperature data of $Ce_{4}Pd_{10}In_{21}$ display ferromagnetic long-range order below 0.8 K.
Źródło:
Acta Physica Polonica A; 2014, 126, 1; 324-325
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Magnetocaloric Effect in Materials with the First Order Transitions - Direct Measurements
Autorzy:
Kamarád, J.
Kaštil, J.
Arnold, Z.
Javorský, P.
Sechovský, V.
Powiązania:
https://bibliotekanauki.pl/articles/1535138.pdf
Data publikacji:
2010-11
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
75.30.Sg
75.30.Kz
75.50.Cc
Opis:
The results of direct measurements of the magneto-caloric characteristics Δ $T_{ad}$ and the indirect determination of Δ $S_{m}$ of pure Gd around the Curie temperature and of the $FeMnP_{0.45}As_{0.55}$ and $Ni_{45}Co_5Mn_{31}Ga_{19}$ intermetallics in the vicinity of the first order magnetic and structural phase transitions are presented and discussed. A pronounced temperature and field dependence of the first order transitions in the studied materials manifests restrictions applying these materials in magnetic refrigeration techniques. An effective use of the Ericsson and the Brayton refrigeration cycles with $FeMnP_{0.45}As_{0.55}$ in the role of a refrigerant is discussed.
Źródło:
Acta Physica Polonica A; 2010, 118, 5; 1000-1001
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Magnetic, Thermal and Transport Properties of $YbPt_2Si_2$ and $Yb_2Pt_3Si_5$ Single Crystals
Autorzy:
Fikáček, J.
Prchal, J.
Sechovský, V.
Powiązania:
https://bibliotekanauki.pl/articles/1371255.pdf
Data publikacji:
2014-07
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
61.50.-f
75.20.En
75.30.Mb
Opis:
Single crystals of $YbPt_{2}Si_{2}$ and $Yb_{2}Pt_{3}Si_{5}$ have been prepared by solvent growth method with Sn flux, characterized by X-ray diffraction and by EDX microprobe analysis and investigated by measurement of magnetization, specific heat and electrical resistivity as functions of temperature and magnetic field. $YbPt_{2}Si_{2} (Yb_{2}Pt_{3}Si_{5})$ crystalizes in the tetragonal $CaBe_{2}Ge_{2}$-type (orthorhombic $U_{2}Co_{3}Si_{5}$-type) structure. Both compounds exhibit metallic resistivity behavior without visible anomaly, which could be connected with onset of magnetic ordering. Neither the specific heat shows any sign of magnetic ordering down to 0.5 K. The corresponding temperature dependences of the magnetic susceptibility of both compounds behave qualitatively similar, which is reminiscent of spin fluctuation behavior: a broad maximum at high temperatures, a shallow minimum at lower temperatures, followed by an upturn with further cooling the crystal, which can be suppressed by applying a sufficient magnetic field. The rather low values of the γ-coefficients of the specific heat (~25÷35 mJ·mol·$K^{-2}$) do not support the mixed valence scenario discussed in literature for $YbPt_{2}Si_{2}$.
Źródło:
Acta Physica Polonica A; 2014, 126, 1; 310-311
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Electronic Structure of $PrCo_2Ge_2$
Autorzy:
Diviš, M.
Vejpravová, J.
Rusz, J.
Prokleška, J.
Sechovský, V.
Powiązania:
https://bibliotekanauki.pl/articles/1813659.pdf
Data publikacji:
2008-01
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
71.15.Mb
71.70.Ch
Opis:
The intermetallic compound $PrCo_2Ge_2$ exhibits very interesting physical properties: antiferromagnetism below $T_N$ = 28 K, an order to order transition at $T_R$ = 8 K, a rich magnetic phase diagram, and huge magnetocrystalline anisotropy as observed by recent experiments on a single crystal in a magnetic field up to 14 T. We performed first principles calculations based on the density functional theory. The localized $4f^2$ configuration of $Pr^{3+}$ was treated using the open core approximation. The electronic densities of states were obtained and the position of the Fermi level was found. The hybridization between the Co-3d, Pr-5d and Ge-4p states is discussed. The calculated magnetic moment of Co is found to be quite small $(m_{Co} < 0.1 μ_B)$. The first principles calculations of the crystal field interaction were performed as well: the obtained crystal field parameters were used as the starting parameters for further refinement in comparison with experimental data of the magnetic susceptibility and specific heat. The crystal field splitting of the 4f states was determined.
Źródło:
Acta Physica Polonica A; 2008, 113, 1; 295-298
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Anomalous Transport Properties of Carbon-Doped $EuB_6$
Autorzy:
Batkova, M.
Batko, I.
Filipov, V.
Flachbart, K.
Sechovský, V.
Shitsevalova, N.
Šantavá, E.
Šebek, J.
Powiązania:
https://bibliotekanauki.pl/articles/1534309.pdf
Data publikacji:
2010-11
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
75.30.Kz
72.15.Gd
75.47.Gk
Opis:
In the presented work we report electrical, magnetic and thermal properties of $EuB_{6-x}C_{x}$ single crystals with an estimated value of x ≈ 0.07. Our studies reveal an antiferromagnetic phase transition at $T_{N}$ ≈ 6.7 K. Electrical resistivity at zero magnetic field shows a pronounced resistivity maximum at $T_{M}$ ≈ 7 K, just above the antiferromagnetic phase transition temperature. With increasing applied magnetic field the maximum moves to lower temperature and becomes totally suppressed at the field of 9 T. Observed magnetoresistance is negative in the whole studied temperature range 2-20 K, yielding a ratio of ρ(0 T, 7 K)/ρ(9 T, 7 K) ≈ 2.5. The origin of such magnetoresistance is associated with formation of mixed magnetic structure in the system due to fluctuation of carbon concentration.
Źródło:
Acta Physica Polonica A; 2010, 118, 5; 893-894
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł

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