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Tytuł:
Mesoscopic Ordering Effects in Single-Crystalline Thin Films of Lanthanum Manganites
Autorzy:
Samoilenko, Z. A.
Okunev, V. D.
Pushenko, E. I.
Abal'oshev, A.
Baran, M.
Gierłowski, P.
Lewandowski, S. J.
Szymczak, R.
Powiązania:
https://bibliotekanauki.pl/articles/2037100.pdf
Data publikacji:
2004
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
75.30.Kz
75.47.Lx
61.50.Ks
Opis:
We have investigated thin films of lanthanum manganites epitaxially grown by pulsed laser deposition on single-crystalline substrates. X-ray diffraction studies show that the characteristic feature of the investigated films is a superposition of fractions with long range atomic order in the basic single-crystalline matrix, and mesoscopic order in the clusterized structure encompassing the Mn-O layers. A detailed analysis of diffusive scattering shows that the size of metallic clusters and their volume concentration in the dielectric matrix varies. In the case of a small size and concentration, the metallic clusters in low temperature behave as quantum dots and their presence leads to a tunneling mechanism of conductivity with characteristic R(T)= const. In the case of large cluster size, the discrete energy levels become smeared. It appears also that the optical, transport, and magnetic properties of the investigated films depend critically on the distribution of Mn$\text{}^{2+}$, Mn$\text{}^{3+}$, and Mn$\text{}^{4+}$ ions in the clusters.
Źródło:
Acta Physica Polonica A; 2004, 105, 1-2; 93-98
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Orbital Correlations and Magnetic Phase Transitions in Lightly Doped La$\text{}_{0.88}$MnO$\text{}_{x}$ and LaMn$\text{}_{0.94}$O$\text{}_{y}$ Manganites
Autorzy:
Troyanchuk, I. O.
Khomchenko, V. A.
Tovar, M.
Szymczak, H.
Bärner, K.
Powiązania:
https://bibliotekanauki.pl/articles/2037044.pdf
Data publikacji:
2004
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
75.30.Kz
75.47.Lx
61.50.Ks
Opis:
The results of X-ray and neutron diffraction study as well as the elastic, magnetic, and electrotransport properties of La$\text{}_{0.88}$MnO$\text{}_{x}$ (2.82≤ x≤2.96) and LaMn$\text{}_{0.94}$O$\text{}_{y}$ (2.91≤ y≤3.00)$ manganites have been presented. Under oxygen doping, the transitions from antiferromagnetic to ferromagnetic or spin-glass state are observed for La-deficient and La-excessive series, respectively. These transitions have been found to correlate with the change of the type of Jahn-Teller distortions from static to dynamic ones. The dynamic orbital correlations favor a ferromagnetic state, while an A-type antiferromagnetic state is typical of the static Jahn-Teller distortions. It is argued that the canting magnetic structure in manganites is not realized. The transition to a ferromagnetic or spin-glass state occurs via the formation of inhomogeneous state with different types of orbital correlations and magnetic structure. The key role of intrinsic chemical inhomogeneity in the formation of inhomogeneous magnetic states in solid solutions of manganites is emphasized.
Źródło:
Acta Physica Polonica A; 2004, 105, 1-2; 27-44
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
The Effect on Highly Cr-Substituted Manganite Nd$\text{}_{0.6}$C a$\text{}_{0.4}$(Mn$\text{}_{0.5}$Cr$\text{}_{0.5}$)O$\text{}_{3}$
Autorzy:
Gamari-Seale, H.
Troyanchuk, I. O.
Bushinsky, M. V.
Stefanopoulos, K. L.
Hernandez-Velasco, J.
Powiązania:
https://bibliotekanauki.pl/articles/2037098.pdf
Data publikacji:
2004
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
75.25.+z
75.30.Kz
75.47.Lx
Opis:
Neutron powder-diffraction experiments on the highly Cr-substituted manganite, Nd$\text{}_{0.6}$Ca$\text{}_{0.4}$(Mn$\text{}_{0.5}$Cr$\text{}_{0.5}$)O$\text{}_{3}$, at different temperatures and fields reveal that the structure retains the charge exchange-type of the parent compound, Nd$\text{}_{0.6}$Ca$\text{}_{0.4}$MnO$\text{}_{3}$. It is antiferromagnetic below 200 K and becomes a canted antiferromagnet below 50 K. The Mn and Cr form zig-zag ferromagnetic chains coupled antiferromagnetically in the ac-plane. These are stacked along the b-axis with opposite spins.
Źródło:
Acta Physica Polonica A; 2004, 105, 1-2; 81-86
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
EMR Study of Electronic and Magnetic Ordering in Doped CaMn$\text{}_{1-x,y}$M$\text{}_{x,y}$O$\text{}_{3}$ (M = Ru, Mo) Perovskites
Autorzy:
Shames, A. I.
Auslender, M.
Rozenberg, E.
Gorodetsky, G.
Martin, C.
Maignan, A.
Powiązania:
https://bibliotekanauki.pl/articles/2043550.pdf
Data publikacji:
2005-08
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
75.30.Kz
75.47.Lx
76.30.-v
76.50.+g
Opis:
X-band electron magnetic resonance measurements of polycrystalline CaMn$\text{}_{1-x,y}$M$\text{}_{x,y}$O$\text{}_{3}$ (M = Ru, 0≤x≤0.5; M = Mo, 0≤y≤0.14) samples were performed at 120 K≤ T≤540 K. The observed anomalies of electron magnetic resonance parameters correlate pretty well with the temperatures of antiferro-, ferromagnetic-like, and orbital/charge-ordering transitions in these systems and specify phase diagrams obtained by other techniques. However, a strong difference between resonant properties of Ru- and Mo-doped series is observed in both paramagnetic and magnetically ordered states. To describe such a difference, the energy bands diagrams, which comprise the deep impurity t$\text{}_{2g}$-like states + e$\text{}_{g}$-like conductive band for CaMn$\text{}_{1-x}$Ru$\text{}_{x}$O$\text{}_{3}$ and shallow impurity states + conductive band, both having e$\text{}_{g}$-like symmetry, for CaMn$\text{}_{1-y}$Mo$\text{}_{y}$O$\text{}_{3}$, are proposed. Specific electrons' contribution to the electron magnetic resonance line width explains concentration and temperature dependences of this parameter in the paramagnetic state in considered systems.
Źródło:
Acta Physica Polonica A; 2005, 108, 2; 235-242
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
High Pulsed Magnetic Field Sensor Based on La-Ca-Mn-O Thin Polycrystalline Films
Autorzy:
Balevičius, S.
Žurauskienė, N.
Stankevič, V.
Keršulis, S.
Novickij, J.
Altgilbers, L. L.
Clarke, F.
Powiązania:
https://bibliotekanauki.pl/articles/2041727.pdf
Data publikacji:
2005-01
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
75.30.Kz
73.40.Gk
85.70.Ay
61.72.Mm
Opis:
It is demonstrated that polycrystalline La$\text{}_{0.33}$Ca$\text{}_{0.67}$MnO$\text{}_{3}$ thin film sensors can be used to measure pulsed strong magnetic fields with microsecond duration rise and decay times. The response characteristics of these sensors were investigated using 0.7-1.0 ms duration bell-shaped magnetic field pulses of 10-20 T amplitudes and by using special waveform magnetic field pulses with amplitudes of 40 T and decay times of 50μs. The response of these magnetic field sensors was compared with those of conventional loop sensors and Faraday rotation sensors using Bi$\text{}_{12}$SiO$\text{}_{20}$ single crystals as a known standard.
Źródło:
Acta Physica Polonica A; 2005, 107, 1; 207-210
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Influence of Pressure on Magnetic Properties of La$\text{}_{1-x}$ Sr$\text{}_{x}$CoO$\text{}_{3-δ}$(x=0.5, 0.67, 1)
Autorzy:
Piętosa, J.
Wiśniewski, A.
Puźniak, R.
Kolesnik, S.
Majjiga, M.
Dabrowski, B.
Powiązania:
https://bibliotekanauki.pl/articles/2046737.pdf
Data publikacji:
2006-04
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
75.30.-m
75.47.Gk
75.30.Kz
Opis:
Influence of pressure on the phase transition temperature T$\text{}_{C}$ and on the spontaneous magnetisation M$\text{}_{0}$ of highly Sr substituted and oxygen nonstoichiometric La$\text{}_{1-x}$Sr$\text{}_{x}$CoO$\text{}_{3-δ}$ samples was investigated. An increase in T$\text{}_{C}$ and M$\text{}_{0}$ with pressure in investigated samples was found, indicating strengthening of ferromagnetic double exchange interactions, and the expansion of volume of ferromagnetic phase as a~result of enhancement in ferromagnetic interactions in both cluster-glass and long range ferromagnetic states. We did not observe clear correlation between changes in pressure coefficient dT$\text{}_{C}$/dP and changes in the formal oxidation state of the Co ion.
Źródło:
Acta Physica Polonica A; 2006, 109, 4-5; 527-532
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Magnetization Processes in Dilute Metamagnets with Ferro- and Antiferromagnetic Exchange Interactions
Autorzy:
Pikuła, R.
Kirkiewicz, J.
Powiązania:
https://bibliotekanauki.pl/articles/2046880.pdf
Data publikacji:
2006-07
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
05.70.Jk
64.60.Kw
75.10.-b
75.30.Kz
Opis:
Using the Green function method there has been presented the mathematical description of dilute two sub-lattice metamagnets with ferro- and antiferromagnetic exchange interactions. The Green function averaging procedure is based on the Cumulant Expansion Technique and includes any localized Green function irrespectively of the decoupling algorithm making the chain system of equations self-consistent. The derived form of the averaged Green function is the base for the analysis of magnetization processes and phase transitions occurring in the system under the influence of external magnetic field. It has been found in particular that the tricritical point and the second-order phase transition vanish when concentrations of magnetic atoms coupled with different sub-lattice points become different.
Źródło:
Acta Physica Polonica A; 2006, 110, 1; 25-39
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Influence of Hydrostatic Pressure on Magnetic Properties of (Sr,La)(Ru,Cr,Mn)O$\text{}_{3}$
Autorzy:
Piętosa, J.
Wiśniewski, A.
Puźniak, R.
Kolesnik, S.
Majjiga, M.
Dabrowski, B.
Powiązania:
https://bibliotekanauki.pl/articles/2047244.pdf
Data publikacji:
2007-01
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
75.30.-m
75.30.Kz
Opis:
An influence of hydrostatic pressure, P, on phase transition temperature, T$\text{}_{C}$, and spontaneous magnetisation, M$\text{}_{0}$, of selected perovskite ruthenates (SrRuO$\text{}_{3}$, La$\text{}_{0.2}$Sr$\text{}_{0.8}$RuO$\text{}_{3}$, SrRu$\text{}_{0.9}$Mn$\text{}_{0.1}$O$\text{}_{3}$, and SrRu$\text{}_{0.9}$Cr$\text{}_{0.1}$O$\text{}_{3}$) was determined to 12 kbar. A decrease in T$\text{}_{C}$ with pressure was found for all of the studied samples. The M$\text{}_{0}$(P) remains unchanged for most of the samples, except for the La$\text{}_{0.2}$Sr$\text{}_{0.8}$RuO$\text{}_{3}$ sample. The weakening of ferromagnetic interactions with increasing pressure is consistent with complex band structure effects related to the modulation of the Ru-O hybridisation by the change of structural distortion.
Źródło:
Acta Physica Polonica A; 2007, 111, 1; 159-163
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Magnetic Phase Transitions in Pure and Cobalt-Doped Geometrically Frustrated Ni$\text{}_{3}$V$\text{}_{2}$O$\text{}_{8}$ Single Crystals
Autorzy:
Szymczak, H.
Baran, M.
Szymczak, R.
Barilo, S. N.
Bychkov, G. L.
Shiryaev, S. V.
Powiązania:
https://bibliotekanauki.pl/articles/2047217.pdf
Data publikacji:
2007-01
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
75.30.Gw
75.30.Kz
75.40.Cx
75.50.-y
Opis:
The results of magnetic measurements performed on geometrically frustrated Ni$\text{}_{3}$V$\text{}_{2}$O$\text{}_{8}$ and Ni$\text{}_{3(1-x)}$Co$\text{}_{3x}$V$\text{}_{2}$O$\text{}_{8}$ single crystals with x=0.03 are presented. It was found that Co doping did not change considerably the magnetic H-T phase diagram. Although no spin-glass effects were observed, nevertheless, a strong effect of 3 at% cobalt doping was evidenced. The main effect of Co-doping concerns the direction of the antiferromagnetic vector, which for Ni$\text{}_{3}$V$\text{}_{2}$O$\text{}_{8}$ appears along the $a$ axis, while for only slightly Co doped crystals - along the $c$ axis. This switching of direction results from distinct changes of the magnetocrystalline anisotropy due to the presence of Co$\text{}^{2+}$ ions strongly coupled to the kagome lattice. The disorder introduced by doping has practically no effect on the magnitude of the isotropic exchange interactions. At the same time the doping suppresses the Dzyaloshinskii-Moriya exchange interactions due to the change of direction of the antiferromagnetic vector.
Źródło:
Acta Physica Polonica A; 2007, 111, 1; 71-77
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
$\text{}^{57}Fe$ Hyperfine Interactions in the $Sc(Fe_{1-x}Ni_x)_2$ Laves Phases Synthesized under High Pressure
Autorzy:
Wiertel, M.
Surowiec, Z.
Budzyński, M.
Tsvyashchenko, A.
Powiązania:
https://bibliotekanauki.pl/articles/1811581.pdf
Data publikacji:
2008-12
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
76.80.+y
77.80.Bh
75.30.Kz
07.35.+k
Opis:
The structural and microscopic magnetic properties of the pseudobinary $Sc(Fe_{1-x}Ni_x)_2$ system prepared under high pressure of 8 GPa were studied by X-ray diffraction and Mössbauer measurements in the range of 0.0 ≤ x ≤ 0.60. The samples for 0.0 ≤ x ≤ 0.10 have the hexagonal C14-type structure and those for 0.30 ≤ x ≤ 0.60 crystallize in the C15-type structure. Both the magnetic hyperfine field on $\text{}^{57}Fe$ and the Curie temperature decrease with the increasing Ni content and the system becomes paramagnetic for x ≈ 0.60 at room temperature. The form and temperature dependences of the Mössbauer spectra for 0.40 ≤ x ≤ 0.50 indicate the coexistence of paramagnetic and ferromagnetic regions in the samples and occurrence of magnetic clusters with a wide distribution of the Curie temperatures. It is interesting that $T_C$ for the compounds obtained under high pressure are by about 100 K smaller in comparison with those for the isostructural samples produced under normal pressure even though interatomic distances are practically equal in the both types of compounds.
Źródło:
Acta Physica Polonica A; 2008, 114, 6; 1517-1527
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
A Dilute Magnet with Ferro- and Antiferromagnetic Exchange Interactions. The Structural Fluctuations Analysis
Autorzy:
Pikuła, R.
Kirkiewicz, J.
Powiązania:
https://bibliotekanauki.pl/articles/1813493.pdf
Data publikacji:
2008-02
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
05.70.Jk
75.30.Kz
Opis:
We analysed the influence of the fluctuations in distribution of magnetic atoms on the properties of dilute magnets with mixed ferro- and antiferromagnetic exchange interactions. The high- and low concentration approximations were found to give very close results and the most important impact on the physical quantities origins from the lowest, square fluctuations which play the predominant role in the whole range of concentrations of magnetic atoms.
Źródło:
Acta Physica Polonica A; 2008, 113, 2; 669-676
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Effect of Chemical Disorder on Geometrically Frustrated Kagome Lattice
Autorzy:
Szymczak, H.
Szymczak, R.
Baran, M.
Fink-Finowicki, J.
Krzymanska, B.
Aleshkevych, P.
Jezierski, A.
Powiązania:
https://bibliotekanauki.pl/articles/1812268.pdf
Data publikacji:
2008-07
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
75.25.+z
75.30.Gw
75.30.Kz
75.50.-
Opis:
This paper reviews recent progress in the studies of magnetic dilutions on magnetic properties of two frustrated systems: magnetoplumbite-like $SrGa_{12-x}Cr_xO_{19}$ and kagome staircase $Co_3V_2O_8$ doped with Mg ions. In the first group of compounds magnetic properties are determined by magnetic defects arising due to doping. In the case of kagome staircase compounds magnetic dilution suppresses effects of crystal field acting on magnetic ions. In particular, the dilution decreases magnetocrystalline anisotropy and anisotropy of magnetization.
Źródło:
Acta Physica Polonica A; 2008, 114, 1; 35-42
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Frustration-Driven Quantum Phase Transition in the 1D Extended Anisotropic Heisenberg Model
Autorzy:
Plekhanov, E.
Avella, A.
Mancini, F.
Powiązania:
https://bibliotekanauki.pl/articles/1813777.pdf
Data publikacji:
2008-01
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
75.10.Jm
75.30.Kz
75.10.Pq
75.40.Mg
Opis:
By using density matrix renormalization group technique we study the 1D extended anisotropic Heisenberg model. We find that starting from the ferromagnetic phase, the system undergoes two quantum phase transitions induced by frustration. By increasing the next-nearest-neighbor interaction, the ground state of the system changes smoothly from a completely polarized state to a next-nearest-neighbor correlated one. On the contrary, letting the in-plane interaction to be greater than the out-of-plane one, the ground state changes abruptly.
Źródło:
Acta Physica Polonica A; 2008, 113, 1; 429-432
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Ground-State Phase Diagram of a Model FCC Magnet with Modified RKKY Interaction
Autorzy:
Szałowski, K.
Balcerzak, T.
Powiązania:
https://bibliotekanauki.pl/articles/1813773.pdf
Data publikacji:
2008-01
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
75.50.Pp
75.10.-b
75.30.Hx
75.30.Kz
Opis:
The ground-state phase diagram is studied for a diluted model magnet with FCC structure and modified Ruderman-Kittel-Kasuya-Yosida interaction. The modification consists in taking into account the exponential damping for the long-range interaction as well as the nearest-neighbors antiferromagnetic superexchange couplings. The existence of paramagnetic, ordered ferromagnetic and three distinct antiferromagnetic phases is shown. The stability areas of the phases upon the free-carriers concentration are investigated.
Źródło:
Acta Physica Polonica A; 2008, 113, 1; 421-424
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Magnetic and Transport Properties of $CeCo_{12}B_6$ and $CeFe_2Co_{10}B_6$ Compounds under Pressure
Autorzy:
Míšek, M.
Arnold, Z.
Skorokhod, Y.
Kamarád, J.
Isnard, O.
Mayot, H.
Powiązania:
https://bibliotekanauki.pl/articles/1813638.pdf
Data publikacji:
2008-01
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
75.10.-b
75.25.+z
75.30.Kz
Opis:
Study of pressure effects on magnetic and transport properties of $CeCo_{12}B_6$ and $CeFe_2Co_{10}B_6$ was performed in temperature range 5-300 K at pressures up to 9 kbar. The significant decrease in the Curie temperature $T_C$ as a consequence of Fe substitution from (135±1) K to (85±1) K is not accompanied by the changes of saturation magnetization. The decrease in $T_C$ with pressure is the same for both samples -Δ$T_C$/Δp ≈ -0.5 K/kbar. The relative decrease in saturation magnetization with pressure is about 0.3%/kbar for both samples. Pressure induced resistivity changes were below 1%. The relatively low pressure effect on both the $T_C$ and magnetization can be attributed to the hybridization as a consequence of small distances between the Co and B atoms.
Źródło:
Acta Physica Polonica A; 2008, 113, 1; 263-266
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł

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