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    Wyświetlanie 1-29 z 29
    Tytuł:
    Magnetic Properties of Zinc Doped Ferrites
    Autorzy:
    Abd El-Ati, M. I.
    Kafafy, Aziz M.
    Tawfik, A.
    Powiązania:
    https://bibliotekanauki.pl/articles/1887816.pdf
    Data publikacji:
    1991-06
    Wydawca:
    Polska Akademia Nauk. Instytut Fizyki PAN
    Tematy:
    75.50.Gg
    75.50.Dd
    Opis:
    A series of samples of the system Co$\text{}_{1-x}$Zn$\text{}_{x}$Fe$\text{}_{2}$O$\text{}_{4}$ (x = 0.0, 0.3, 0.4, 0.5 and 0.8) have been prepared by the usual ceramic technique. X-ray analysis shows that they are cubic spinel (single phase). The lattice parameter a and the bulk density D are measured for the samples. The substitution experiments replacing Co$\text{}^{2+}$ by Zn$\text{}^{2+}$ furnish new significant fact concerning the magnetic behaviour of ferrites. The magnetic strength of the magnetic ions on the Band A-sites can be varried relative to each other by the substitution of Zn$\text{}^{2+}$. The increase of density of the composition increases the magnetic interaction of the dipole moment at the B-sites.
    Źródło:
    Acta Physica Polonica A; 1991, 79, 6; 889-894
    0587-4246
    1898-794X
    Pojawia się w:
    Acta Physica Polonica A
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    On the Question of Ferromagnetism in Proton and He-Irradiated Carbon
    Autorzy:
    Szczytko, J.
    Juszyński, P.
    Teliga, L.
    Twardowski, A.
    Stonert, A.
    Ratajczak, R.
    Korman, A.
    Powiązania:
    https://bibliotekanauki.pl/articles/1811995.pdf
    Data publikacji:
    2008-11
    Wydawca:
    Polska Akademia Nauk. Instytut Fizyki PAN
    Tematy:
    75.20.Ck
    75.50.Dd
    Opis:
    We tried to repeat the observation of the ferromagnetic response in proton and He-irradiated carbon made by the group of Esquinazi et al. We used $He^+$ and $H^+$ beams focused on graphite sample. The amount of charge deposited in the sample was comparable to the amount of charge used by Esquinazi. Magnetic measurements were performed in SQUID magnetometer. The magnetization of the samples before and after irradiation was compared. We did not observe any ferromagnetic enhancement of magnetization of our irradiated samples. Even if experiment was not the same as Esqinazi's one, we can exclude some of the mechanisms of ferromagnetism proposed by Esquinazi.
    Źródło:
    Acta Physica Polonica A; 2008, 114, 5; 1387-1390
    0587-4246
    1898-794X
    Pojawia się w:
    Acta Physica Polonica A
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    High Spin-Low Spin Transitions in $Cu_{0.2}Co_{0.76}Cr_{1.83}Se_4$ Semiconductor
    Autorzy:
    Maciążek, E.
    Groń, T.
    Pacyna, A.
    Mydlarz, T.
    Krok-Kowalski, J.
    Powiązania:
    https://bibliotekanauki.pl/articles/1489908.pdf
    Data publikacji:
    2012-03
    Wydawca:
    Polska Akademia Nauk. Instytut Fizyki PAN
    Tematy:
    75.30.Wx
    75.50.Dd
    75.50.Ee
    Opis:
    Magnetization, ac and dc magnetic susceptibility measured in the zero-field-cooled mode were used to study the high spin-low spin transitions in polycrystalline $Cu_{0.2}Co_{0.76}Cr_{1.83}Se_4$ semiconductor. The real part component of fundamental susceptibility $χ_1^\prime$ (T) and its second $(χ_2)$ and third $(χ_3)$ harmonics revealed two spectacular peaks at 128 K and at 147 K, confirming the appearance of the spin-crossover phenomenon.
    Źródło:
    Acta Physica Polonica A; 2012, 121, 3; 687-689
    0587-4246
    1898-794X
    Pojawia się w:
    Acta Physica Polonica A
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Spin Crossover in Cu$\text{}_{x}$Co$\text{}_{y}$Cr$\text{}_{z}$Se$\text{}_{4}$ Semiconductors
    Autorzy:
    Maciążek, E.
    Groń, T.
    Pacyna, A. W.
    Mydlarz, T.
    Zawisza, B.
    Krok-Kowalski, J.
    Powiązania:
    https://bibliotekanauki.pl/articles/2048134.pdf
    Data publikacji:
    2011-05
    Wydawca:
    Polska Akademia Nauk. Instytut Fizyki PAN
    Tematy:
    75.30.Wx
    75.50.Dd
    75.50.Ee
    Opis:
    Magnetization and magnetic susceptibility measured in the zero-field-cooled mode were used to study the spin crossover transition in polycrystalline Cu$\text{}_{x}$Co$\text{}_{y}$Cr$\text{}_{z}$Se$\text{}_{4}$ compounds. With increasing Co content a transition from ferromagnetic order via ferrimagnetic one to antiferromagnetic-like behaviour was observed. This transition is accompanied with a lowering symmetry from cubic to monoclinic and for the latter the spin crossover phenomenon occurs. These results are considered in a framework of the ligand-field split and the spin-orbit coupling.
    Źródło:
    Acta Physica Polonica A; 2011, 119, 5; 711-713
    0587-4246
    1898-794X
    Pojawia się w:
    Acta Physica Polonica A
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Transport and Magnetic Properties of Low Temperature Annealed Ga$\text{}_{1-x}$Mn$\text{}_{x}$As
    Autorzy:
    Kuryliszyn, I.
    Wojtowicz, T.
    Liu, X.
    Furdyna, J. K.
    Dobrowolski, W.
    Broto, J.-M.
    Goiran, M.
    Portugall, O.
    Rakoto, H.
    Raquet, B.
    Powiązania:
    https://bibliotekanauki.pl/articles/2035604.pdf
    Data publikacji:
    2002
    Wydawca:
    Polska Akademia Nauk. Instytut Fizyki PAN
    Tematy:
    75.50.Pp
    75.50.Dd
    81.40.Rs
    Opis:
    We present the results of low temperature annealing studies of Ga$\text{}_{1-x}$Mn$\text{}_{x}$As epilayers grown by low temperature molecular beam epitaxy in a wide range of Mn concentrations (0.01
    Źródło:
    Acta Physica Polonica A; 2002, 102, 4-5; 659-665
    0587-4246
    1898-794X
    Pojawia się w:
    Acta Physica Polonica A
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Mictomagnetic Order in Cd$\text{}_{0.87}$Cr$\text{}_{1.93}$V$\text{}_{0.06}$Se$\text{}_{4}$ Semiconductor
    Autorzy:
    Groń, T.
    Malicka, E.
    Zawisza, B.
    Duda, H.
    Krok-Kowalski, J.
    Pacyna, A. W.
    Powiązania:
    https://bibliotekanauki.pl/articles/2048136.pdf
    Data publikacji:
    2011-05
    Wydawca:
    Polska Akademia Nauk. Instytut Fizyki PAN
    Tematy:
    72.80.Jc
    75.50.Pp
    75.50.Dd
    Opis:
    The complex ac dynamic magnetic susceptibility was used to study the mictomagnetic-like behavior in polycrystalline Cd$\text{}_{0.87}$Cr$\text{}_{1.93}$V$\text{}_{0.06}$Se$\text{}_{4}$ spinel. The temperature dependences of the zero field in-phase (real part) and out-of-phase (imaginary part) components of fundamental susceptibility measured at the oscillating field H$\text{}_{ac}$ = 0.5 Oe and at the constant frequency of 125 Hz are characteristic for the mictomagnetic order. These results well correlate with the anomalies in the second and third harmonics of the ac susceptibility indicating the cluster glass.
    Źródło:
    Acta Physica Polonica A; 2011, 119, 5; 714-716
    0587-4246
    1898-794X
    Pojawia się w:
    Acta Physica Polonica A
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Hopkinson-Like Effect in Single-Crystalline $CdCr_2Se_4$ and $Cd[Cr_{1.89}Ti_{0.08}]Se_4$
    Autorzy:
    Malicka, E.
    Groń, T.
    Pacyna, A.
    Duda, H.
    Krok-Kowalski, J.
    Powiązania:
    https://bibliotekanauki.pl/articles/1489913.pdf
    Data publikacji:
    2012-03
    Wydawca:
    Polska Akademia Nauk. Instytut Fizyki PAN
    Tematy:
    72.80.Jc
    75.50.Pp
    75.50.Dd
    Opis:
    The static (dc) and dynamic (ac) magnetic measurements of $CdCr_2Se_4$ and $Cd[Cr_{1.89}Ti_{0.08}]Se_4$ showed their ferromagnetic properties with a Curie temperature $T_{C}$ ≈ 130 K and revealed on the real component of ac susceptibility curve, the peaks near $T_{C}$ at 200 Oe, 450 Oe and 1 kOe, characteristic for the Hopkinson ones. The meaningful reduction of saturation moment to 4.73 $μ_{B}$/f.u. for $Cd[Cr_{1.89}Ti_{0.08}]Se_4$ suggests the diamagnetic configuration of Ti ions, which dilutes the ferromagnetic sublattice of Cr ones and causes reducing of the energy losses visible on the imaginary components of ac susceptibility curve. Close for zero values of higher susceptibility harmonics above $T_{C}$ are pointing out to the lack of the spin fluctuations in the paramagnetic state.
    Źródło:
    Acta Physica Polonica A; 2012, 121, 3; 690-693
    0587-4246
    1898-794X
    Pojawia się w:
    Acta Physica Polonica A
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Electrical and Magnetic Characterization οf $ZnCr_{2-x}V_{x}Se_{4}$ Spinel Semiconductors
    Autorzy:
    Duda, H.
    Malicka, E.
    Groń, T.
    Pacyna, A.
    Kusz, J.
    Powiązania:
    https://bibliotekanauki.pl/articles/1791367.pdf
    Data publikacji:
    2009-11
    Wydawca:
    Polska Akademia Nauk. Instytut Fizyki PAN
    Tematy:
    72.80.Jc
    75.50.Pp
    75.50.Dd
    Opis:
    Single crystals of $ZnCr_{2}Se_{4}$ spinel doped with vanadium were prepared by chemical vapour transport. The chemical compositions of three crystals have been determined by X-ray diffraction. The structure refinement using the SHELXL-93 program system determine the cation distribution in the system as $ZnCr_{2-x}V_{x}Se_{4}$. For x values equal to 0.03, 0.1 and 0.13 the observed symmetry was cubic, space group Fd3m. Based on the structural data, influence of the V ions on the magnetic and electrical properties has been analyzed.
    Źródło:
    Acta Physica Polonica A; 2009, 116, 5; 962-963
    0587-4246
    1898-794X
    Pojawia się w:
    Acta Physica Polonica A
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Electrical and Magnetic Studies of the $Cd_{x}Cr_{y}V_{z}Se_{4}$ Spinels
    Autorzy:
    Groń, T.
    Duda, H.
    Malicka, E.
    Zawisza, B.
    Krok-Kowalski, J.
    Pacyna, A.
    Powiązania:
    https://bibliotekanauki.pl/articles/1791407.pdf
    Data publikacji:
    2009-11
    Wydawca:
    Polska Akademia Nauk. Instytut Fizyki PAN
    Tematy:
    72.80.Jc
    75.50.Pp
    75.50.Dd
    Opis:
    The electrical and magnetic investigations carried out on the polycrystalline spinels with the general chemical formula $Cd_{x}Cr_{y}V_{z}Se_{4}$ (where z = 0.06, 0.12, 0.24, and 0.31) revealed semiconducting and ferromagnetic properties with a Curie temperature of 127.5 K. A step-like structure of the electrical conductivity, σ(T), was observed for the polycrystal containing 6% V ions in the octahedral sites while the remaining samples showed a typical Arrhenius behaviour of σ(T). These effects are interpreted in terms of ferromagnetic spin clusters which finally dissolve on going towards the paramagnetic limit including non-stoichiometry.
    Źródło:
    Acta Physica Polonica A; 2009, 116, 5; 969-970
    0587-4246
    1898-794X
    Pojawia się w:
    Acta Physica Polonica A
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Ferromagnetic Order in Single-Crystalline (Cd$\text{}_{x}$Al$\text{}_{y}$)[Cr$\text{}_{2}$]Se$\text{}_{z}$ Semiconductors
    Autorzy:
    Duda, H.
    Rduch, P.
    Malicka, E.
    Groń, T.
    Kusz, J.
    Powiązania:
    https://bibliotekanauki.pl/articles/2048125.pdf
    Data publikacji:
    2011-05
    Wydawca:
    Polska Akademia Nauk. Instytut Fizyki PAN
    Tematy:
    72.80.Jc
    75.50.Pp
    75.50.Dd
    Opis:
    Measurements of the magnetic properties, the electrical conductivity and the Seebeck effect were performed on single crystals (Cd$\text{}_{x}$Al$\text{}_{y}$)[Cr$\text{}_{2}$]Se$\text{}_{z}$ between 77 and 300 K. All samples have a ferromagnetic order with the Curie temperature of 130 K and the paramagnetic Curie-Weiss temperature of 155 K. Both these temperatures do not depend significantly on the Al substitution. The electrical conductivity of single crystals CdCr$\text{}_{2}$Se$\text{}_{4}$ doped with Al was p-type and showed the change of log σ versus 1/T slope above 150 K. This fact is interpreted as being due to the onset of impurity conduction and structural defects.
    Źródło:
    Acta Physica Polonica A; 2011, 119, 5; 702-704
    0587-4246
    1898-794X
    Pojawia się w:
    Acta Physica Polonica A
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Competing Magnetic Interactions in Zn$\text{}_{3}$Fe$\text{}_{4}$V$\text{}_{6}$O$\text{}_{24}$ Studied by Electron Paramagnetic Resonance
    Autorzy:
    Zolnierkiewicz, G.
    Guskos, N.
    Typek, J.
    Blonska-Tabero, A.
    Powiązania:
    https://bibliotekanauki.pl/articles/2046813.pdf
    Data publikacji:
    2006-04
    Wydawca:
    Polska Akademia Nauk. Instytut Fizyki PAN
    Tematy:
    76.30.-v
    75.50.Dd
    75.50.Ee
    Opis:
    A multicomponent vanadate M$\text{}_{3}$Fe$\text{}_{4}$V$\text{}_{6}$O$\text{}_{24}$ sample with non-magnetic M = Zn(II) ions was synthesized by the solid state reaction method using stoichiometric mixtures of the 80mol% FeVO$\text{}_{4}$ and 20mol% Zn$\text{}_{3}$(VO$\text{}_{4}$)$\text{}_{2}$. The temperature dependence of the EPR spectra was performed in the 90-280 K temperature range. The resonance field and the integrated intensity of the EPR line showed minimum value of both parameters at≈200 K. It is suggested that a part of the sample is displaying tendency to form an antiferromagnetic ordered state (or the magnetic clusters) above this temperature while below the ferromagnetic interaction of the main part of material is dominating. This behaviour is attributed to the inherent magnetic inhomogeneity of the system due to the presence of the ferromagnetic or antiferromagnetic spin clusters.
    Źródło:
    Acta Physica Polonica A; 2006, 109, 4-5; 675-679
    0587-4246
    1898-794X
    Pojawia się w:
    Acta Physica Polonica A
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Ferromagnetism in Cr-Based Diluted Magnetic Semiconductors
    Autorzy:
    Blinowski, J.
    Kacman, P.
    Majewski, J. A.
    Powiązania:
    https://bibliotekanauki.pl/articles/1933725.pdf
    Data publikacji:
    1995-10
    Wydawca:
    Polska Akademia Nauk. Instytut Fizyki PAN
    Tematy:
    71.70.Gm
    75.50.Pp
    75.50.Dd
    Opis:
    It has been recently established that in zinc chalcogenides with Cr$\text{}^{2+}$ paramagnetic ions the p-d interactions are ferromagnetic. We clarify the origins of this property and make predictions concerning other Cr-based diluted magnetic semiconductors. The observation of the ferromagnetic p-d interaction resuscitated hopes for ferromagnetic d-d exchange interactions in diluted magnetic semiconductors. We have calculated the nearest-neighbor superexchange integrals in Cr-based diluted magnetic semiconductors. No simple correlation between the signs of p-d and d-d interactions has been found. Still, there are extended energy regions where the calculated superexchange is ferromagnetic and the act ual parameters of DMS with Cr$\text{}^{2+}$ seem to match these regions.
    Źródło:
    Acta Physica Polonica A; 1995, 88, 4; 683-686
    0587-4246
    1898-794X
    Pojawia się w:
    Acta Physica Polonica A
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    New Discussion of the Spin Dynamics of Paramagnetic EuO
    Autorzy:
    Latacz, Z.
    Powiązania:
    https://bibliotekanauki.pl/articles/2038379.pdf
    Data publikacji:
    2004-10
    Wydawca:
    Polska Akademia Nauk. Instytut Fizyki PAN
    Tematy:
    75.40.Gb
    75.40.Cx
    75.50.Dd
    Opis:
    The simplest approximations for a continued-fraction representation of the dynamic relaxation function are used to investigate the spin dynamics of paramagnetic EuO. As the result we can see how the considered approximations predict those wavevectors for which a "spin wave" peak appears in the spectrum. Furthermore, the calculated position of this peak is compared with experiment. The correlation theory within the two-pole approximation is presented in a simple and analytic form.
    Źródło:
    Acta Physica Polonica A; 2004, 106, 4; 515-528
    0587-4246
    1898-794X
    Pojawia się w:
    Acta Physica Polonica A
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    On the Kinetic Exchange in A$\text{}^{III}$B$\text{}^{V}$ Diluted Magnetic Semiconductors
    Autorzy:
    Blinowski, J.
    Kacman, P.
    Powiązania:
    https://bibliotekanauki.pl/articles/2027499.pdf
    Data publikacji:
    2001-09
    Wydawca:
    Polska Akademia Nauk. Instytut Fizyki PAN
    Tematy:
    71.70.Gm
    75.50.Dd
    75.30.Et
    Opis:
    In the case of II-VI diluted magnetic compounds it was shown that the kinetic exchange mechanism depends crucially on the electronic configuration of the magnetic ions and the charge transfer energies for the transitions from the band onto the magnetic ion and vice versa. In the present paper we analyze these effects in the family of III-V diluted magnetic semiconductors, showing that they affect considerably the predictions of the values of the Curie temperature and should be taken into account in the search for room temperature ferromagnetism in diluted magnetic semiconductors.
    Źródło:
    Acta Physica Polonica A; 2001, 100, 3; 343-349
    0587-4246
    1898-794X
    Pojawia się w:
    Acta Physica Polonica A
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Critical Behaviour of the Mean-Field Ferromagnet $Cu_{1.02}[Cr_{1.77}Ti_{0.24}]Se_4$
    Autorzy:
    Krok-Kowalski, J.
    Władarz, G.
    Rduch, P.
    Malicka, E.
    Groń, T.
    Guzik, A.
    Powiązania:
    https://bibliotekanauki.pl/articles/1409626.pdf
    Data publikacji:
    2012-12
    Wydawca:
    Polska Akademia Nauk. Instytut Fizyki PAN
    Tematy:
    75.40.Cx
    75.50.Dd
    64.60.Ht
    Opis:
    Magnetization, M, and susceptibility, χ, measurements showed both strong lowering of magnetic moment in comparison with $CuCr_2Se_4$ matrix and zero-field-cooling-field-cooling susceptibility splitting characteristic for the spin-glass behaviour. Isothermal magnetization curves, M(H), easy saturate and large values both of the Curie $T_{C}$=253 K and Curie-Weiss θ=283.5 K temperatures indicate the ferromagnetic order which coexists with the spin-glass state. The critical behaviour investigated around the paramagnetic-ferromagnetic phase transition revealed that the values of critical exponents are close to those predicted by the mean field model for long-range magnetic interactions.
    Źródło:
    Acta Physica Polonica A; 2012, 122, 6; 1102-1104
    0587-4246
    1898-794X
    Pojawia się w:
    Acta Physica Polonica A
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Control of Ferromagnetism in Cd$\text{}_{1-x}$Mn$\text{}_{x}$Te Based Quantum Wells
    Autorzy:
    Bertolini, M.
    Boukari, H.
    Ferrand, D.
    Cibert, J.
    Tatarenko, S.
    Gilles, B.
    Maślana, W.
    Gaj, J. A.
    Kossacki, P.
    Dietl, T.
    Powiązania:
    https://bibliotekanauki.pl/articles/2035587.pdf
    Data publikacji:
    2002
    Wydawca:
    Polska Akademia Nauk. Instytut Fizyki PAN
    Tematy:
    75.30.Hx
    75.50.Dd
    75.50.Pp
    78.55.Et
    Opis:
    New structures aiming at controlling the ferromagnetic properties of diluted magnetic semiconductor quantum wells are presented. The carrier density is controlled by applying a voltage across a p-i-n diode. A new method, creating a 2D hole gas by adjusting the distance between the quantum well and surface, offers opportunities for a broader range of structures.
    Źródło:
    Acta Physica Polonica A; 2002, 102, 4-5; 603-608
    0587-4246
    1898-794X
    Pojawia się w:
    Acta Physica Polonica A
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Magnetism in Doped Two-Dimensional Honeycomb Structures of III-V Binary Compounds
    Autorzy:
    Zberecki, K.
    Powiązania:
    https://bibliotekanauki.pl/articles/1428644.pdf
    Data publikacji:
    2012-05
    Wydawca:
    Polska Akademia Nauk. Instytut Fizyki PAN
    Tematy:
    73.22.-f
    75.50.Pp
    75.50.Dd
    75.70.Ak
    Opis:
    Using first-principles plane-wave calculations study of magnetic properties of doped two-dimensional honeycomb structures of III-V binary compounds have been conducted for either nonmagnetic dopants or vacancies. Calculations show that all cases where magnetic moment is non-zero, are energetically more favorable. For such cases band structure and density of states were calculated and analyzed in detail. The possible applications of these structures were also discussed.
    Źródło:
    Acta Physica Polonica A; 2012, 121, 5-6; 1240-1241
    0587-4246
    1898-794X
    Pojawia się w:
    Acta Physica Polonica A
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Ferromagnetism in II-VI Based Semiconductor Structures
    Autorzy:
    Cibert, J.
    Ferrand, D.
    Tatarenko, S.
    Wasiela, A.
    Kossacki, P.
    Dietl, T.
    Powiązania:
    https://bibliotekanauki.pl/articles/2027470.pdf
    Data publikacji:
    2001-08
    Wydawca:
    Polska Akademia Nauk. Instytut Fizyki PAN
    Tematy:
    72.80.Ey
    75.50.Pp
    75.30.Hx
    75.50.Dd
    Opis:
    The experimental results on carrier-induced ferromagnetic interaction in II-VI diluted magnetic semiconductors are shortly reviewed and analyzed in the light of the mean field approximation. We particularly take the point of view of the experimentalist to emphasize (i) points which are easily understood within this simple model (as the role of the detailed structure of the valence band) and hence should be incorporated into more sophisticated models, and (ii) points which are not taken into account in the mean field model (e.g., disorder effects) and hence call for more elaborate descriptions. We particularly discuss the case of a low carrier density, and show that the situation appears as experimentally very different in the highly disordered 3D layers and in the modulation doped 2D quantum wells.
    Źródło:
    Acta Physica Polonica A; 2001, 100, 2; 227-236
    0587-4246
    1898-794X
    Pojawia się w:
    Acta Physica Polonica A
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Investigation of Heterostructure Formed from Hole- and Electron-Doped Lanthanum Manganites
    Autorzy:
    Vengalis, B.
    Rosa, A. M.
    Devenson, J.
    Šliužienė, K.
    Lisauskas, V.
    Oginskis, A.
    Anisimovas, F.
    Pyragas, V.
    Powiązania:
    https://bibliotekanauki.pl/articles/2041760.pdf
    Data publikacji:
    2005-02
    Wydawca:
    Polska Akademia Nauk. Instytut Fizyki PAN
    Tematy:
    73.40.Cg
    73.40.Lg
    75.50.Dd
    Opis:
    High crystalline quality films of n-La$\text{}_{2}\text{}_{/}\text{}_{3}$ Ce$\text{}_{1}\text{}_{/}\text{}_{3}$ MnO$\text{}_{3}$, p-La$\text{}_{2}\text{}_{/}\text{}_{3}$ Ca$\text{}_{1}\text{}_{/}\text{}_{3}$ MnO$\text{}_{3}$ and related p-n diode structures were grown heteroepitaxially on lattice-matched SrTiO$\text{}_{3}$(100) substrates by dc magnetron sputtering and pulsed laser deposition. The La$\text{}_{2}\text{}_{/}\text{}_{3}$ Ce$\text{}_{1}\text{}_{/}\text{}_{3}$ Mn O$\text{}_{3}$/La$\text{}_{2}\text{}_{/}\text{}_{3}$ Ca$\text{}_{1}\text{}_{/}\text{}_{3}$ MnO$\text{}_{3}$ bilayer was patterned into a strip-like geometry to investigate electrical properties of the interface. Significant magnetoresistance values and nonlinear current-voltage characteristics were indicated for the interface of the p-n diode heterostructure.
    Źródło:
    Acta Physica Polonica A; 2005, 107, 2; 290-293
    0587-4246
    1898-794X
    Pojawia się w:
    Acta Physica Polonica A
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Effect of Vanadium Substitution of Cobalt in $NdCo_2Si_2$
    Autorzy:
    Chowdhury, R.
    Dhara, S.
    Bandyopadhyay, B.
    Powiązania:
    https://bibliotekanauki.pl/articles/1402070.pdf
    Data publikacji:
    2015-10
    Wydawca:
    Polska Akademia Nauk. Instytut Fizyki PAN
    Tematy:
    71.20.Lp
    75.50.Gg
    75.50.Ee
    75.50.Cc
    75.50.Dd
    Opis:
    In NdCo₂Si₂, partial substitution of Co by V having a larger atomic radius results in negative pressure affecting the magnetic properties of the compound. The samples $Nd(Co_{1-x}V_{x})_Si_2$ (x=0, 0.20, 0.35) have been prepared and characterized using X-ray diffraction. The parent compound NdCo₂Si₂ is antiferromagnetic with $T_{N}$ of 34 K whereas the temperature dependence of inverse susceptibility in the doped samples show ferrimagnetic behaviour below 45 K. From the magnetic field dependence of magnetization and the coercive fields obtained from hysteresis loops, the doped samples exhibit ferromagnetism below ≈ 20 K. The specific heat studies compare the magnetic transitions in the parent and doped samples. $Nd(Co_{0.65}V_{0.35})_2Si_2$ shows a magnetoresistance of 15% at 4 K.
    Źródło:
    Acta Physica Polonica A; 2015, 128, 4; 530-532
    0587-4246
    1898-794X
    Pojawia się w:
    Acta Physica Polonica A
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Ferromagnetic Ground State of Two-Band Hubbard Model with One Electron per Site
    Autorzy:
    Schulenburg, J.
    Richter, J.
    Powiązania:
    https://bibliotekanauki.pl/articles/1955522.pdf
    Data publikacji:
    1997-02
    Wydawca:
    Polska Akademia Nauk. Instytut Fizyki PAN
    Tematy:
    75.40.Mg
    75.30.Et
    75.50.Dd
    75.10.Lp
    Opis:
    We study the multiband mechanism to favour a ferromagnetic insulating ground state within a two-band Hubbard model. Besides perturbation theory we use exact diagonalization studies to examine the ground state of chains and 2D-lattices. According to second order perturbation theory the exact diagonalization yields a fully polarized ferromagnetic ground state, if the hopping between two ground state orbitals of neighbouring atoms t$\text{}_{gg}$ is small and the hopping between a ground state orbital and an excited orbital t$\text{}_{ge}$ dominates. However, in contrast to the suggestion from the second order perturbation theory this ferromagnetic state is stable only for very small hopping integrals U≫ t$\text{}_{ge}$>t$\text{}_{gg}$. For larger t $\text{}_{ge}$ quantum interference effects lead to complex magnetic structures.
    Źródło:
    Acta Physica Polonica A; 1997, 91, 2; 367-370
    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:
    Structure and Transport Properties of La$\text{}_{0.75-x}$RE$\text{}_{x}$Ca$\text{}_{0.25}$MnO$\text{}_{3}$ (RE = Gd, Dy, Ho; 0≤ x≤0.75) Manganites
    Autorzy:
    Drozd, V.
    Pękała, M.
    Kovac, J.
    Skorvanek, I.
    Szymański, M.
    Nedilko, S.
    Powiązania:
    https://bibliotekanauki.pl/articles/2041482.pdf
    Data publikacji:
    2004-11
    Wydawca:
    Polska Akademia Nauk. Instytut Fizyki PAN
    Tematy:
    75.47.Lx
    71.38.-k
    72.20.Ee
    75.50.Dd
    Opis:
    Structure and transport properties have been studied for a series of La$\text{}_{0.75-x}$RE$\text{}_{x}$Ca$\text{}_{0.25}$MnO$\text{}_{3}$ manganites with heavy rare earth ions of Gd, Dy, Ho substituting La with x=0, 0.10, 0.25, 0.50, and 0.75. Polycrystalline samples were prepared by the carbonate precipitation route. The oxygen content was determined by the iodometric titration. The X-ray investigations carried out by the powder method show that the unit cell volume gradually decreases and orthorhombic distortion of the lattice increases with rising RE content. Below the room temperature the electrical resistivity is of the semiconducting type for all the samples studied. Electrical resistivity vs. temperature dependences were analyzed within different models: simple thermal activation, Mott's variable range hopping, adiabatic, nonadiabatic, and bipolaron. The Curie temperatures of Gd, Dy, and Ho substituted manganites determined from magnetization measurements show that at 280 K all the samples are in the paramagnetic phase. The increasing RE fraction reduces magnetization at 4 K as compared to La$\text{}_{0.75}$Ca$\text{}_{0.25}$MnO$\text{}_{3}$.
    Źródło:
    Acta Physica Polonica A; 2004, 106, 5; 751-758
    0587-4246
    1898-794X
    Pojawia się w:
    Acta Physica Polonica A
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Quantum versus Classical Polarons in a Ferromagnetic $CuO_3$-Like Chain
    Autorzy:
    Bieniasz, K.
    Oleś, A.
    Powiązania:
    https://bibliotekanauki.pl/articles/1374771.pdf
    Data publikacji:
    2014-10
    Wydawca:
    Polska Akademia Nauk. Instytut Fizyki PAN
    Tematy:
    72.10.Di
    75.10.Pq
    75.50.Dd
    79.60.-i
    Opis:
    We present an exact solution for an itinerant hole added into the oxygen orbitals of a $CuO_{3}$-like ferromagnetic chain. Using the Green function method, the quantum polarons obtained for the Heisenberg SU(2) interaction between localized Cu spins are compared with the polarons in the Ising chain. We find that magnons with large energy are favorable towards quasiparticle existence, even in the case of relatively modest electron-magnon coupling. We observe two quasiparticle states with dispersion ~2t each, which emerge from the incoherent continuum when the exchange coupling J increases. Quantum fluctuations in the spin system modify the incoherent part of the spectrum and change the spectral function qualitatively, beyond the bands derived from the perturbation theory.
    Źródło:
    Acta Physica Polonica A; 2014, 126, 4a; A-80-A-83
    0587-4246
    1898-794X
    Pojawia się w:
    Acta Physica Polonica A
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Field-Induced Magnetic Order in Frustrated $TbBaCo_4O_7$ Single Crystals
    Autorzy:
    Szymczak, R.
    Bludov, A.
    Gnatchenko, S.
    Barilo, S.
    Jezierski, A.
    Szymczak, H.
    Powiązania:
    https://bibliotekanauki.pl/articles/1536830.pdf
    Data publikacji:
    2010-08
    Wydawca:
    Polska Akademia Nauk. Instytut Fizyki PAN
    Tematy:
    75.30.Cr
    75.30.Gw
    75.30.Kz
    75.60.Ej
    75.50.Dd
    Opis:
    We present results of dc magnetic susceptibility measurements in $TbBaCo_4O_7$ single crystals performed at temperatures in the range 2-300 K and in magnetic fields up to 55 kOe. The results obtained seem to suggest that the ground state of $TbBaCo_4O_7$ is composed of coexisting long-range ordered and short-range ordered clusters and is transformed into a magnetically ordered weak ferromagnetic phase by application high magnetic field along c-axis.
    Źródło:
    Acta Physica Polonica A; 2010, 118, 2; 299-302
    0587-4246
    1898-794X
    Pojawia się w:
    Acta Physica Polonica A
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Negative Magnetisation and Absence of Superconductivity in RFe$\text{}_{4}$Al$\text{}_{8}$ (R=Lu, Yb) Compounds
    Autorzy:
    Andrzejewski, B.
    Kowalczyk, A.
    Toliński, T.
    Powiązania:
    https://bibliotekanauki.pl/articles/2046747.pdf
    Data publikacji:
    2006-04
    Wydawca:
    Polska Akademia Nauk. Instytut Fizyki PAN
    Tematy:
    74.70.Dd
    75.50.-y
    75.50.Ee
    51.60.+a
    74.70.-b
    Opis:
    We report researches for superconductivity and the effect of negative magnetisation in the RFe$\text{}_{4}$Al$\text{}_{8}$ (R = Lu, Yb) compounds by means of magnetic measurements and microwave absorption. Contrary to the earlier reports we do not confirm the existence of any traces of superconductivity in these compounds. Instead of the superconductivity and the Meissner effect, the YbFe$\text{}_{4}$Al$\text{}_{8}$ compound exhibits the effect of negative magnetisation, whereas the LuFe$\text{}_{4}$Al$\text{}_{8}$ compound shows an exact antiferromagnetic behaviour.
    Źródło:
    Acta Physica Polonica A; 2006, 109, 4-5; 561-564
    0587-4246
    1898-794X
    Pojawia się w:
    Acta Physica Polonica A
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Layer and Interface Structure of CoFe/Ru Multilayers
    Autorzy:
    Pym, A.
    Lamperti, A.
    Cardoso, S.
    Freitas, P.
    Tanner, B.
    Powiązania:
    https://bibliotekanauki.pl/articles/1814028.pdf
    Data publikacji:
    2007-12
    Wydawca:
    Polska Akademia Nauk. Instytut Fizyki PAN
    Tematy:
    61.10.Kw
    68.65.Ac
    68.35.Ct
    75.50.Kj
    85.75.Dd
    85.70.Ay
    Opis:
    Grazing incidence X-ray scattering measurements have been performed to probe the structure of CoFe/Ru layers and their interfaces. It was found that the interface width increased approximately linearly with the layer number from the substrate in a multilayer and that a substantial asymmetry existed between the width of CoFe/Ru and Ru/CoFe interfaces. By co-minimizing both the specular and diffuse scatter with that simulated from a model structure, the topological roughness amplitude was determined to be comparable to the intermixing interface width.
    Źródło:
    Acta Physica Polonica A; 2007, 112, 6; 1243-1248
    0587-4246
    1898-794X
    Pojawia się w:
    Acta Physica Polonica A
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Observation of Superconductivity in Highly Cr-Doped GaP Single Crystals
    Autorzy:
    Gosk, J. B.
    Strzelecka, G.
    Kowalski, G.
    Hruban, A.
    Kamińska, M.
    Twardowski, A.
    Gronkowski, J.
    Powiązania:
    https://bibliotekanauki.pl/articles/2046913.pdf
    Data publikacji:
    2006-08
    Wydawca:
    Polska Akademia Nauk. Instytut Fizyki PAN
    Tematy:
    74.10.+v
    75.50.Pp
    61.72.Vv
    61.72.Dd
    81.10.Dn
    Opis:
    Studying bulk GaP, highly doped with Cr, and searching for possible ferromagnetic semiconductor in view of spintronic applications, we found superconducting behavior of this material unexpectedly. Magnetization techniques and X-ray diffraction were applied to study these crystals. Magnetization revealed superconducting features up to about 6 K and X-ray studies showed that superconductivity might be related to small size Cr precipitates.
    Źródło:
    Acta Physica Polonica A; 2006, 110, 2; 189-193
    0587-4246
    1898-794X
    Pojawia się w:
    Acta Physica Polonica A
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Superconductivity Study of GaN Highly Doped by Transition Metals
    Autorzy:
    Gosk, J.
    Boćkowski, M.
    Tokarczyk, M.
    Kowalski, G.
    Twardowski, A.
    Powiązania:
    https://bibliotekanauki.pl/articles/1399142.pdf
    Data publikacji:
    2013-11
    Wydawca:
    Polska Akademia Nauk. Instytut Fizyki PAN
    Tematy:
    74.25.Ha
    74.70.-b
    74.25.Dw
    75.50.-y
    61.72.Dd
    81.10.Dn
    Opis:
    GaN:Cr and GaN:Fe single crystals as well as GaN:Mn micropowders highly doped by transition metals were grown to investigate low temperature superconductivity. Magnetic measurements revealed type I superconductivity with $T_{C} ≈ 6 K$ and $H_{C} ≈ 600 Oe$, identical for all compounds and also identical to that observed before in GaP:Cr and GaAs:Cr. The presence of amorphous inclusions of gallium may explain existing superconductivity as a result of a phase transition leading to β-Ga during cooling down of the sample. Since the observed parameters are close to those characteristic for superconducting Ga(II) this possibility could not be ruled out.
    Źródło:
    Acta Physica Polonica A; 2013, 124, 5; 877-880
    0587-4246
    1898-794X
    Pojawia się w:
    Acta Physica Polonica A
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
      Wyświetlanie 1-29 z 29

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