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Wyszukujesz frazę "Flachbart, K." wg kryterium: Autor


Wyświetlanie 1-12 z 12
Tytuł:
Investigation of Mixed Valence State of $Sm_{1-x}B_{6}$ and $Sm_{1-x}La_{x}B_{6}$ by XANES
Autorzy:
Gabáni, S.
Flachbart, K.
Bednarčík, J.
Welter, E.
Filipov, V.
Shitsevalova, N.
Powiązania:
https://bibliotekanauki.pl/articles/1371509.pdf
Data publikacji:
2014-07
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
78.70.Dm
71.28.+d
71.27.+a
Opis:
We investigated the valence states of samarium ions in Sm deficient $Sm_{1-x}B_{6}$ (x=0.03, 0.05, 0.08, 0.1 and 0.2) sintered samples, in single crystalline solid solutions $Sm_{1-x}La_{x}B_{6}$ (x=0.16, 0.28, 0.4, 0.55 and 0.7) as well as in a $SmB_{6}$ single crystal by X-ray absorption near edge structure (XANES) between 4.2 and 300 K. It was shown that the mixed valence state $v_{Sm}$ of Sm-ions ($v_{Sm}$ ≈ 2.51 for $SmB_{6}$ at 4.2 K) in deficient samples is changed but maintained up to a concentration of 20% of vacancies and up to a concentration of 70% in samples doped with trivalent La-ions, and that in both cases it increases with temperature. On the other hand, the value of $v_{Sm}$ increases with increasing vacancy level, whereas it decreases with increasing $La^{3+}$ substitution. The obtained dependences of Sm-valence in $SmB_{6}$ on vacancy as well as on $La^{3+}$ ion concentration are in good agreement with susceptibility measurements and exact numerical calculation of the spinless Falicov-Kimball model in two dimensions.
Źródło:
Acta Physica Polonica A; 2014, 126, 1; 338-339
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Magnetic Phase Diagram of $TmB_{4}$ under High Pressure
Autorzy:
Gabáni, S.
Pristáš, G.
Takáčová, I.
Flachbart, K.
Filipov, V.
Shitsevalova, N.
Siemensmeyer, K.
Powiązania:
https://bibliotekanauki.pl/articles/1371562.pdf
Data publikacji:
2014-07
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
75.30.Kz
75.25.+z
74.25.F
62.50.-p
Opis:
$TmB_{4}$ is a Shastry-Sutherland frustrated system which exhibits very complex magnetic properties. In this contribution the phase diagram of magnetic field vs. temperature of $TmB_{4}$ under hydrostatic pressure up to 26.5 kbar is investigated using sensitive ac-resistance measurements. Temperature and magnetic field dependences of resistance at various pressures were carried out in a piston cylinder pressure cell between 1.7 and 14 K and in magnetic fields up to 6 T. The obtained results exhibit shifts of ordering temperatures $T_{N}$ as well as shifts of boundaries between different magnetic phases. The observed pressure dependences of $T_{N}$ can be described by the relation d $lnT_{N}$/dp=+(0.16÷0.18) %/kbar. The effect of pressure on various interactions between magnetic ions in this compound is discussed.
Źródło:
Acta Physica Polonica A; 2014, 126, 1; 356-357
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Angular Dependences of ESR Parameters in Antiferroquadrupolar Phase of CeB₆
Autorzy:
Semeno, A.
Gilmanov, M.
Sluchanko, N.
Krasnorussky, V.
Shitsevalova, N.
Filipov, V.
Flachbart, K.
Demishev, S.
Powiązania:
https://bibliotekanauki.pl/articles/1032654.pdf
Data publikacji:
2017-04
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
76.30.-v
76.30.Kg
Opis:
Angular dependences of ESR line parameters (g-factor and linewidth Δ H) were experimentally explored in the antiferroquadrupolar phase of heavy fermion system CeB₆ at T=1.8 K. The data were obtained in two experimental geometries with different mutual directions of the wavevector k and the external magnetic field H at frequency of f=60 GHz. A g-factor anisotropy was found: while g-factors for [110] and [111] directions are close to each other (g ≈1.6), it is considerably higher (g ≈1.75) for [100]. The obtained angular dependence g(Θ) was compared with the theoretically predicted g-factor behavior for the Γp₈ state of Ce³⁺ ion in antiferroquadrupolar phase of CeB₆. It turns out that the experimental g-factor is considerably smaller at all angles than the theoretically calculated limits (2
Źródło:
Acta Physica Polonica A; 2017, 131, 4; 1060-1062
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
Tytuł:
Phonon Drag and Magnetic Anomalies of Thermopower in $RB_{12}$ (R = Ho, Er, Tm, Lu)
Autorzy:
Glushkov, V.
Demishev, S.
Ignatov, M.
Khayrullin, E.
Sluchanko, N.
Shitsevalov, N.
Levchenko, A.
Filipov, V.
Flachbart, K.
Siemensmeyer, K.
Powiązania:
https://bibliotekanauki.pl/articles/1813647.pdf
Data publikacji:
2008-01
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
72.15.Jf
75.50.Ee
Opis:
High precision measurements of the Seebeck coefficient S(T) were carried out on the single crystals of $RB_{12}$ (R = Ho, Er, Tm, Lu) at temperatures 2-300 K. It was shown that the effects of phonon drag result from vibrations of rare earth ions ($ħω_E$≈10-33 meV) in the rigid framework structure of the $B_{12}$ clusters and determine the main contribution to thermopower at intermediate temperatures (30-300 K). The correlated behavior of transport parameters favors the appreciable enhancement of spin fluctuations in the sequence of magnetic compounds $(HoB_{12}-TmB_{12})$ when approaching to the valence instability state in $YbB_{12}$. The giant increase in S(T) detected in the vicinity of the Néel temperature $T_N$ for $HoB_{12},$ $ErB_{12},$ and $TmB_{12}$ seems to result from the density of states renormalization caused by antiferromagnetic ordering.
Źródło:
Acta Physica Polonica A; 2008, 113, 1; 275-278
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Influence of pressure on the electrical transport properties of carbon-doped EuB₆
Autorzy:
Pristáš, G.
Gabáni, S.
Baťko, I.
Baťková, M.
Orendáč, M.
Gažo, E.
Filipov, V.
Konovalova, E.
Diko, P.
Flachbart, K.
Powiązania:
https://bibliotekanauki.pl/articles/1053101.pdf
Data publikacji:
2017-04
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
74.62.Fj
75.30.Kz
Opis:
We have studied the influence of hydrostatic pressure on the electrical resistivity of carbon-doped semimetal EuB₆ which orders ferromagnetically at T_{C}=3.9 K and is intrinsically inhomogeneous due to fluctuations of carbon content. We observed a shift of the low-temperature resistivity maximum from 4.6 K (at 1 bar) to 5.2 K (at 30.3 kbar) with increasing pressure. However, the maximum of the derivative dρ/dT(T), which reveals the temperature of ferromagnetic ordering, does not change its position with increasing pressure. This behaviour is different from stoichiometric EuB₆, where pressure increases the ferromagnetic ordering temperature. The origin of this discrepancy may lie in the increase of volume fraction of the non-ferromagnetic phase with increase of pressure. Additional magnetoresistance measurements at various pressures between 1.5 K and 30 K have shown that with increase of magnetic field the resistivity is monotonically decreasing, and above 1 T a transition to a monotonic resistivity behaviour (dρ/dT(T)>0) is observed. Our results support the picture that carbon-rich regions play a role of "spacers", which prevent the percolation of the ferromagnetic phase.
Źródło:
Acta Physica Polonica A; 2017, 131, 4; 982-984
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Bulk and Local Magnetic Susceptibility of $ErB_{12}$
Autorzy:
Bogach, A.
Bogomolov, L.
Glushkov, V.
Demishev, S.
Sluchanko, D.
Sluchanko, N.
Shitsevalova, N.
Levchenko, A.
Filipov, V.
Flachbart, K.
Siemensmeyer, K.
Powiązania:
https://bibliotekanauki.pl/articles/1813645.pdf
Data publikacji:
2008-01
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
72.15.Eb
75.50.Ee
Opis:
High precision measurements of magnetoresistance Δρ/ρ = f(T,H) and magnetization M(T,H) were carried out on single crystals of rare-earth dodecaboride $ErB_{12}$ at temperatures in the interval 1.8-30 K in magnetic fields up to 70 kOe. The high accuracy of the experiments allowed us to perform numerical differentiation and analyze quantitatively the behavior of the derivative d(Δρ/ρ)/dH = f(T,H) and of the magnetic susceptibility χ(T,H) = dM/dH in paramagnetic and magnetically ordered (antiferromagnetic, $T_N$ ≈ 6.7 K and $T_M$ ≈ 5.85 K) phases of $ErB_{12}$. It was shown that negative magnetoresistance anomalies observed in present study in paramagnetic state of $ErB_{12}$ may be consistently interpreted in the framework of a simple relation between resistivity and magnetization -Δρ/ρ ~ $M^2$.
Źródło:
Acta Physica Polonica A; 2008, 113, 1; 271-274
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Anisotropy of the charge transport in GdB₆
Autorzy:
Anisimov, M.
Glushkov, V.
Bogach, A.
Demishev, S.
Samarin, N.
Samarin, A.
Shitsevalova, N.
Levchenko, A.
Filipov, V.
Gábani, S.
Flachbart, K.
Sluchanko, N.
Powiązania:
https://bibliotekanauki.pl/articles/1052920.pdf
Data publikacji:
2017-04
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
72.15.Gd
Opis:
The anisotropy of charge transport was investigated in the antiferromagnetic II state of GdB₆ from precise measurements of transverse magnetoresistance. Based on the data obtained we detected a complicated behavior of magnetoresistance curves which are characterized by the appearance of considerable hysteresis on the field and angular dependences below T_{N2}. Moreover it was shown that the system GdB₆ is sensitive to cooling-warming prehistory. The data analysis allowed to reconstruct magnetic H-T phase diagram of GdB₆ along main crystallographic directions (H||⟨001⟩,⟨110⟩,⟨111⟩) and to propose additional phase transition inside AF II phase at H₁ ≈ 0.5 T.
Źródło:
Acta Physica Polonica A; 2017, 131, 4; 973-975
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Charge Transport and Magnetism in $Eu_{1-x}Ca_{x}B_6$
Autorzy:
Glushkov, V.
Anisimov, M.
Batko, I.
Batkova, M.
Bogach, A.
Demishev, S.
Filipov, V.
Flachbart, K.
Kuznetsov, A.
Sannikov, I.
Shitsevalova, N.
Sluchanko, N.
Powiązania:
https://bibliotekanauki.pl/articles/1534292.pdf
Data publikacji:
2010-11
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
71.30.+h
75.30.Cr
75.40.-s
75.47.Gk
Opis:
Transport, magnetic and thermal properties of substitutional solid solution $Eu_{1 - x}Ca_{x}B_6$ single crystals (0 ≤ x ≤ 0.244) have been studied at 1.8 ≤ T ≤ 300 K and in magnetic fields up to 8 T. Calcium doping is shown to result in a metal-insulator transition, which occurs at x_{MIT} ≈ 0.2. In vicinity of metal-insulator transition the effect of colossal magnetoresistance is found to be very sensitive to Ca content, the amplitude varying from Δ = [ ρ (0)- ρ (8T)]/ρ(8T) ≈1.4 × $10^2$ to Δ ≈ 7.5 × $10^3$ for 0.14 ≤ x ≤ 0.16. The analysis of magnetic contribution to heat capacity shows that a large amount of magnetic entropy ( ≈ 30%) releases in $Eu_{0.845}Ca_{0.155}B_6$ when moving from the Curie temperature $T_{C}$ ≈ 5.5 K to the characteristic one T* ≈ 30 K. This observation as well as the large amplitude of low field colossal magnetoresistance effect and the deviation of magnetic susceptibility from the Curie-Weiss law detected for x = 0.155 compound in the interval $T_{C}$ ≤ T ≤ T* seem to be associated with magnetic phase separation induced by Ca doping.
Źródło:
Acta Physica Polonica A; 2010, 118, 5; 891-892
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Anisotropy of Magnetoresistance in HoB₁₂
Autorzy:
Khoroshilov, A.
Krasnorussky, V.
Bogach, A.
Glushkov, V.
Demishev, S.
Levchenko, A.
Shitsevalova, N.
Filipov, V.
Gabáni, S.
Flachbart, K.
Anisimov, M.
Siemensmeyer, K.
Sluchanko, N.
Powiązania:
https://bibliotekanauki.pl/articles/1032153.pdf
Data publikacji:
2017-04
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
71.27.+a
Opis:
We present results of precision measurements of magnetoresistance of isotopically pure Ho¹¹B₁₂ at low temperatures 2÷10 K in magnetic field up to 80 kOe of different orientation to the crystal axes. The data obtained revealed strong anisotropy of magnetoresistance and allowed us to reconstruct magnetic H-T phase diagrams for main crystallographic directions H || [001], [110], and [111]. Analysis of magnetoresistance derivatives allowed to conclude in favor of two main magnetoresistance contributions. Among of them the negative quadratic component is attributed to charge carriers scattering on a magnetic clusters of Ho³⁺ ions (4f component) and positive linear one may be explained in terms of scattering on a spin density waves (5d component).
Źródło:
Acta Physica Polonica A; 2017, 131, 4; 976-978
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Magnetoresistance Anisotropy and Magnetic H-T Phase Diagram of $Tm_{0.996}Yb_{0.004}B_{12}$
Autorzy:
Sluchanko, N.
Azarevich, A.
Bogach, A.
Glushkov, V.
Demishev, S.
Gavrilkin, S.
Gabani, S.
Flachbart, K.
Shitsevalova, N.
Filipov, V.
Vanacken, J.
Moshchalkov, V.
Stankiewicz, J.
Powiązania:
https://bibliotekanauki.pl/articles/1371466.pdf
Data publikacji:
2014-07
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
72.15.Gd
73.43.Qt
75.30.Kz
75.20.Hr
75.50.Ee
Opis:
The antiferromagnetic ground state has been studied by transverse magnetoresistance, heat capacity and magnetization measurements, which were carried out on high quality single crystals of $Tm_{0.996}Yb_{0.004}B_{12}$ dodecaboride in strong magnetic fields at liquid helium temperatures. Both antiferromagnetic-paramagnetic (AF-P) and spin-orientation (AF1-AF2) phase transitions have been observed, and allowed to construct a complicated magnetic H-T phase diagram for this compound. Strong magnetoresistance anisotropy was found both in AF states (ρ(H||[110])/ρ(H||[111])~ 1.2 at H~ 20 kOe) and at the critical field of AF-P transition $(H_{N}[100]$/$H_{N}[111]$~ 1.25) in this magnetic metal with a simple fcc crystal structure.
Źródło:
Acta Physica Polonica A; 2014, 126, 1; 332-333
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Charge Transport and Magnetism in $Tm_{0.03}Yb_{0.97}B_{12}$
Autorzy:
Glushkov, V.
Azarevich, A.
Anisimov, M.
Bogach, A.
Demishev, S.
Dukhnenko, A.
Filipov, V.
Flachbart, K.
Gabáni, S.
Gavrilkin, S.
Kondrin, M.
Shitsevalova, N.
Sluchanko, N.
Powiązania:
https://bibliotekanauki.pl/articles/1398286.pdf
Data publikacji:
2017-04
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
72.15.Gd
72.15.Jf
71.27.+a
Opis:
Transport and magnetic properties of polycrystalline $Tm_{0.03}Yb_{0.97}B_{12}$ samples were investigated at temperatures 1.8-300 K in magnetic fields up to 9 T. The activated behavior of resistivity, the Hall coefficient and thermopower is described in terms of a narrow gap $ε_g$ ≈ 16.6 meV, which controls the charge transport in $Tm_{0.03}Yb_{0.97}B_{12}$ at T>40 K. The maximum of magnetic susceptibility found at 50 K is shown to be induced by a spin gap Δ ≈ 4.7 meV being close to the half of the spin fluctuation energy in YbB₁₂. Large diffusive thermopower S=AT, A=-29.1 μV/K² and the Pauli susceptibility χ₀ ≈ 7.2×10¯³ emu/mol found below 20 K seem to be associated with the many-body resonance, which corresponds to states with an enhanced effective mass m* ≈ 250m₀ (m₀ - free electron mass). The effective parameters of magnetic centers and the analysis of anomalies favor the nonequivalent states of substitute Tm ions.
Źródło:
Acta Physica Polonica A; 2017, 131, 4; 985-987
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
    Wyświetlanie 1-12 z 12

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