Full-text resources of PSJD and other databases are now available in the new Library of Science.
Visit https://bibliotekanauki.pl
Preferences help
Polish version English version Language
enabled [disable] Abstract
Number of results

Results found: 16

Number of results on page
first rewind previous Page / 1 next fast forward last

Search results

help Sort By:

help Limit search:
first rewind previous Page / 1 next fast forward last
1
Content available remote

Solution Growth and Investigation of the Single Crystals from the CePdIn System

100%
Kratochvílová M., Custers J., Sechovský V.
|
|
vol. 126
|
issue 1
324-325
EN
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.
2
Content available remote

Magnetic, Thermal and Transport Properties of YbPt_2Si_2 and Yb_2Pt_3Si_5 Single Crystals

100%
Fikáček J., Prchal J., Sechovský V.
|
|
vol. 126
|
issue 1
310-311
EN
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}.
3
Content available remote

Magnetic Structure in UIrAl

100%
Prokeš K., Prchal J., Sechovský V., Andreev A.
Acta Physica Polonica A
|
2008
|
vol. 113
|
issue 1
339-342
EN
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.
4
Content available remote

Magnetic Phase Transitions and Thermal Properties of Ho(Co_{1-x}Si_x)_2 Compounds

100%
Vasylyev D., Prokleška J., Sechovský V.
Acta Physica Polonica A
|
2008
|
vol. 113
|
issue 1
347-350
EN
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.
5
Content available remote

Anisotropic Magnetic Properties of URhIn₅ Compound

88%
Bartha A., Kratochvílová M., Sechovský V., Custers J., Dušek M.
Acta Physica Polonica A
|
2015
|
vol. 127
|
issue 2
339-341
EN
We report on synthesis and anisotropic physical properties of URhIn₅. High quality single crystals were grown from In self-flux. The compound undergoes a second-order phase transition into an antiferromagnetic state at T_{N} = 98 K. The transition is magnetic field independent up to 9 T. An increase of the resistivity ρ with j along the [100], [110] and [001] tetragonal axis indicates a spin-density-wave induced order with the gap opening first along the [001] direction. The magnetic susceptibility χ = M/H exhibits a strong anisotropy. Above T= 200 K, χ(T) follows the Curie-Weiss law with the effective moment of μ_{eff} = 3.71 μ_{B}/U and the Weiss temperatures of θ_{P}^{[100]} = -900 K and θ_{P}^{[001]} = -500 K for H ∥ [100] and H ∥ [001], respectively. The characteristic Kondo-like temperature for URhIn₅ yields T_{K}= 125 K.
6
Content available remote

Magnetism in TmCo₂

88%
Šebesta J., Prchal J., Valenta J., Kratochvílová M., Sechovský V.
Acta Physica Polonica A
|
2015
|
vol. 127
|
issue 2
379-381
EN
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.
7
Content available remote

Magnetocaloric Effect in Materials with the First Order Transitions - Direct Measurements

88%
Kamarád J., Kaštil J., Arnold Z., Javorský P., Sechovský V.
|
|
issue 5
1000-1001
EN
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.
8
Content available remote

Electronic Structure of PrCo_2Ge_2

88%
Diviš M., Vejpravová J., Rusz J., Prokleška J., Sechovský V.
Acta Physica Polonica A
|
2008
|
vol. 113
|
issue 1
295-298
EN
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.
9
Content available remote

Presence of Parimagnetism in Ho(Co_{1-x}Si_{x})_{2} Under Hydrostatic Pressure

88%
Valenta J., Prchal J., Kratochvílová M., Míšek M., Sechovský V.
|
|
vol. 126
|
issue 1
406-408
EN
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.
10
Content available remote

Magnetic Properties of a Novel CeCo_{0.715}Si_{2.285} Compound

88%
Moudřík J., Prokleška J., Pospíšil J., Sechovský V., Císařová I.
|
EN
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.
11
Content available remote

Magnetism in UCo_{0.88}Ru_{0.12}Ge Studied by Polarized Neutrons

76%
Vališka M., Pospíšil J., Nénert G., Stunault A., Prokeš K., Sechovský V.
|
|
vol. 126
|
issue 1
330-331
EN
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.
12
Content available remote

Magnetocaloric Effect in CsDy(MoO₄)₂

76%
Tarasenko R., Tkáč V., Orendáčová A., Orendáč M., Sechovský V., Feher A.
Acta Physica Polonica A
|
2018
|
vol. 133
|
issue 3
414-416
EN
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.
13
Content available remote

Thermal Conductivity of a Layered CsGd(MoO_4)_2 Crystal

76%
Tibenská K., Tkáč V., Orendáčová A., Orendáč M., Feher A., Šebek J., Sechovský V.
|
|
issue 5
971-972
EN
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.
14
Content available remote

Scattering of Phonons in CsMnCl_3·2H_2O

64%
Tkáč V., Tibenská K., Orendáčová A., Orendáč M., Šebek J., Sechovský V., Anders A., Feher A.
|
|
issue 5
950-952
EN
The thermal conductivity of the quasi-one-dimensional S = 5/2 Heisenberg antiferromagnet CsMnCl_3·2H_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.
15
Content available remote

Anomalous Transport Properties of Carbon-Doped EuB_6

64%
Batkova M., Batko I., Filipov V., Flachbart K., Sechovský V., Shitsevalova N., Šantavá E., Šebek J.
|
|
issue 5
893-894
EN
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.
16
Content available remote

Magnetism in RCo_{2} (R = Dy, Ho, Er, Tm) Under Hydrostatic Pressure

64%
Prchal J., Šebesta J., Valenta J., Míšek M., Turčinková D., Lapčák L., Prokleška J., Kratochvílová M., Sechovský V.
|
|
vol. 126
|
issue 1
288-289
EN
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}.
first rewind previous Page / 1 next fast forward last
JavaScript is turned off in your web browser. Turn it on to take full advantage of this site, then refresh the page.