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Wyszukujesz frazę "Szymczak, S" wg kryterium: Autor


Wyświetlanie 1-8 z 8
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:
Magnetic Properties of Spin-Ladders (A$\text{}_{2}$Cu$\text{}_{2}$O$\text{}_{3}$)$\text{}_{m}$ (CuO$\text{}_{2}$)$\text{}_{n}$
Autorzy:
Baran, M.
Szymczak, H.
Szymczak, R.
Dyeyev, S.
Leonyuk, L.
Babonas, G.-J.
Powiązania:
https://bibliotekanauki.pl/articles/2013220.pdf
Data publikacji:
2000-03
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
75.40.Cx
75.30.Gw
75.45.+j
75.90.+w
Opis:
Magnetization M(T) and M(H) data of single crystals of the S=1/2 quasi-one-dimensional system (A$\text{}_{2}$Cu$\text{}_{2}$O$\text{}_{3}$)$\text{}_{m}$(CuO$\text{}_{2}$)$\text{}_{n}$ with various A-site constituents are compared. The studied orthorhombic, incommensurate crystals are characterized by m/n=5/7,7/10, and 9/13. The role of rare-earth ions located in A-sites is discussed.
Źródło:
Acta Physica Polonica A; 2000, 97, 3; 571-574
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Electrical Transport and Magnetic Properties of La$\text{}_{2}\text{}_{/}\text{}_{3}$ Pb$\text{}_{1}\text{}_{/}\text{}_{3}$ MnO$\text{}_{3}$ Thin Films
Autorzy:
Baran, M.
Berkowski, M.
Fink-Finowicki, J.
Lewandowski, S. J.
Szymczak, H.
Szymczak, R.
Khartchev, S. I.
Medvedev, Yu. V.
Powiązania:
https://bibliotekanauki.pl/articles/2037109.pdf
Data publikacji:
2004
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
75.30.-m
72.15.Gd
75.70.Pa
Opis:
The magnetic and transport properties of epitaxial La$\text{}_{2}\text{}_{/}\text{}_{3}$ Pb$\text{}_{1}\text{}_{/}\text{}_{3}$ CuO$\text{}_{3}$ thin films deposited on SrLaGaO$\text{}_{4}$ substrate using dc magnetron sputtering technique are reported. The giant magnetoresistance effect (of about 50% at magnetic field of 1 T) was observed near the Curie temperature. Several mechanisms responsible for temperature dependence of resistivity are discussed. The effect of annealing was studied. It shifted the Curie temperature to the lower value, probably, because of the loss of oxygen.
Źródło:
Acta Physica Polonica A; 2004, 105, 1-2; 115-120
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Magnetic Properties of EuBaCo$\text{}_{2}$O$\text{}_{5.5}$ Single Crystals
Autorzy:
Baran, M.
Barilo, S. N.
Bychkov, G. L.
Gatalskaya, V. I.
Kurochkin, L. A.
Shiryaev, S. V.
Szymczak, R.
Szymczak, H.
Powiązania:
https://bibliotekanauki.pl/articles/2037131.pdf
Data publikacji:
2004
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
75.30.Cr
75.50.Dd
75.30.Gw
75.30.Kz
Opis:
The static magnetization of the EuBaCo$\text{}_{2}$O$\text{}_{5.5}$ single crystals was measured from helium to room temperatures for two configurations of the applied field: parallel and perpendicular to the c-axis. The compound is antiferromagnetic from helium temperature to about 210 K. In low temperature region (below 45 K) the antiferromagnetism coexists with a spin-glass-like state. The metamagnetic field-induced phase transition was observed in the antiferromagnetic phase for magnetic field applied perpendicular to the c-axis. The spontaneous phase transition from antiferromagnetic to weak ferromagnetic phase was established to be of the first order. This transition is accompanied by the appearance of the intermediate state. The weak ferromagnetic phase exists up to T$\text{}_{c}$=240 K.
Źródło:
Acta Physica Polonica A; 2004, 105, 1-2; 209-214
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Ellipsometric Studies of NdMnO$\text{}_{3}$ Single Crystals
Autorzy:
Babonas, G. J.
Reza, A.
Szymczak, R.
Baran, M.
Shiryaev, S.
Fink-Finowicki, J.
Szymczak, H.
Powiązania:
https://bibliotekanauki.pl/articles/2037130.pdf
Data publikacji:
2004
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
71.20.-b
78.20.Ci
Opis:
Ellipsometric studies of NdMnO$\text{}_{3}$ single crystals of orthorhombic symmetry were carried out in the spectral range 0.5-5.0 eV. Experimental data, which were obtained on the (001)$\text{}_{pc}$-type planes of pseudo-cubic system, were analyzed in the model of biaxial crystal. For the first time, three componentsε$\text{}_{x}$,ε$\text{}_{y}$,ε$\text{}_{z}$ of the effective dielectric function for manganites of orthorhombic symmetry were determined. From ellipsometric data, the spectra of optical conductivity and loss function were also calculated and considered. The fine structure of the spectra and optical anisotropy was the basis for discussion of the microscopic origin of the optical transitions responsible for the optical features. The electronic excitations due to dipole-forbidden spin-allowed transitions of the d-d-type in Mn-ions, f-f-type in Nd-ions and charge-transfer 2p(O)-3d(Mn) transitions were taken into account. The data for NdMnO$\text{}_{3}$ were compared with those obtained for other related undoped and doped single crystals of perovskite-type structure, LaMnO$\text{}_{3}$, (LaBa)(MnCo)O$\text{}_{3}$ and (LaCa)CoO$\text{}_{3}$.
Źródło:
Acta Physica Polonica A; 2004, 105, 1-2; 197-208
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Structural, Magnetic and Transport Properties οf $NdBaCo_{2}O_{5+x}$ Thin Films Deposited by Magnetron Sputtering
Autorzy:
Vlakhov, E.
Szymczak, R.
Baran, M.
Piotrowski, K.
Szewczyk, A.
Paszkowicz, W.
Lobanovskii, L.
Matyajasik, S.
Nenkov, K.
Szymczak, H.
Powiązania:
https://bibliotekanauki.pl/articles/1810303.pdf
Data publikacji:
2009-01
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
75.70.Ak
64.75.St
64.75.Lm
Opis:
For the first time, thin films of $NdBaCo_{2}O_{5+x}$ were deposited by RF magnetron sputtering on different substrates. The films deposited on $SrLaAlO_4(001)$ substrates exhibited highly textured structure with c-axis directed out-of-plane. Magnetic measurements M vs. T of three $NdBaCo_{2}O_{5+x}$/$SrLaAlO_4(001)$ films revealed successively paramagnetic-ferromagnetic-antiferromagnetic transitions with decrease in temperature. Their paramagnetic Curie-Weiss temperatures were estimated to be in the range of $T_{C}$ =100-116 K. Resistivity of the cobaltite thin film exhibited insulating behavior and the best fit was found for the variable range hopping mechanism.
Źródło:
Acta Physica Polonica A; 2009, 115, 1; 89-91
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
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:
Atomic Order and the Interaction of Electronic and Magnetic Subsystems in Epitaxial LaSr(Ca)MnO Films
Autorzy:
Okunev, V. D.
Samoilenko, Z. A.
D'yachenko, T.
Abal'oshev, A.
Baran, M.
Gierłowski, P.
Lewandowski, S. J.
Szewczyk, A.
Szymczak, R.
Powiązania:
https://bibliotekanauki.pl/articles/2037110.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 the structure, and electric, optical, and magnetic properties of LaSr(Ca)MnO films containing atomic clusters of various types coherently built into the basic crystallographic matrix. Below the transition to the metallic state, the electrical conductivity of the films is determined by tunneling of charge carriers between metallic clusters. We have found that for each sample there exists a threshold value of magnetic ordering, above which the magnetic subsystem starts to affect actively the film conductivity. The observed increase of conductivity with decreasing temperature is caused by the fact that in the process of magnetic ordering of the samples the cluster size and concentration of metallic phase increase. Experimental results are in agreement with theoretical calculations.
Źródło:
Acta Physica Polonica A; 2004, 105, 1-2; 121-126
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
    Wyświetlanie 1-8 z 8

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