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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:
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:
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:
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:
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 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:
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:
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:
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:
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:
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:
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:
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:
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

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