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1

EPR in Kagome Staircase Compound Mg_{2.997}Co_{0.003}V_2O_8

100%

Aleshkevych P., Fink-Finowicki J.

Acta Physica Polonica A

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2007

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vol. 111

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issue 1

105-110

EN

The paramagnetic resonance of Co^{2+} ions in Mg_{2.997}Co_{0.003}V_2O_8 single crystals are reported. The EPR spectrum shows two groups of resonance lines associated with two crystallographically nonequivalent Co ions positions that are known in the kagome staircase system as "cross-tie" and "spine" sites. No preferential occupation of Co^{2+} ions in the kagome lattice was observed. The ground state was described by spin-Hamiltonian with an effective electronic spin S=1/2 and nuclear spin I=7/2. The local symmetry of oxygen octahedron surrounding Co ions, main values of the g-factors, and hyperfine structure were determined for both cobalt positions.

2

Magnon Excitations in Manganites

81%

Aleshkevych P., Baran M., Szymczak H.

Acta Physica Polonica A

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2004

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vol. 106

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issue 5

593-602

EN

A review of experimental studies of magnon excitations in manganites is presented. Two kinds of techniques: the inelastic neutron scattering (in bulk materials) and the microwave resonance (in thin films) are considered. Experimental studies of spin dynamics by inelastic neutron scattering in metallic ferromagnetic manganites have shown that at low temperature for small wave vectors k → 0 the dispersion relation has a quadratic shape similar to that observed in Heisenberg ferromagnets. However, the above technique although very informative can be used only for sufficiently large samples of bulk materials. A complementary microwave resonance technique allows studying not only bulk properties, but also surface properties. There are two main theoretical approaches used to interpret the spin wave resonance spectra: the volume inhomogeneity and the surface inhomogeneity models. The last one introduced by Puszkarski has allowed for interpretation of the observed surface magnon excitations in thin films.

3

Geometrically Frustrated Kagome Lattice with Chemical Disorder

62%

Szymczak R., Baran M., Fink-Finowicki J., Krzymanska B., Aleshkevych P., Szymczak H.

Acta Physica Polonica A

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2008

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vol. 113

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issue 1

413-416

EN

The effect of nonmagnetic Mg^{2+} and magnetic Co^{2+} doping in Kagome compounds was investigated using DC magnetic susceptibility. The main effect of doping is to change the crystal field parameters. It was shown that Co^{2+} doping increases considerably crystal field parameters in Ni_3V_2O_8 while doping with nonmagnetic Mg^{2+} ions decreases considerably crystal field parameters in Co_3V_2O_8 crystals.

4

Spin-Glass Transition in the RCoGaO_{4} (R=Lu, Yb) Layered Cobaltites

62%

Radelytskyi I., Szymczak R., Dabkowska H., Noad H., Aleshkevych P., Szymczak H.

Acta Physica Polonica A

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2014

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vol. 126

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issue 1

230-231

EN

The frequency, temperature, and the dc and ac dependences of the magnetic susceptibility of the YbCoGaO_{4} and LuCoGaO_{4} single crystals are investigated. The YbCoGaO_{4} behaves like an Ising spin glass with a strong uniaxial anisotropy. In contrast LuCoGaO_{4} is Heisenberg-like spin glass. Dynamical scaling reveals a three dimensional phase transition near Tg and yields critical exponent values between those of Heisenberg- andIsing-like systems.

5

Effect of Chemical Disorder on Geometrically Frustrated Kagome Lattice

62%

Szymczak H., Szymczak R., Baran M., Fink-Finowicki J., Krzymanska B., Aleshkevych P., Jezierski A.

Acta Physica Polonica A

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2008

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vol. 114

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issue 1

35-42

EN

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.

6

Signature of the Spin Triplet Phase in La_{0.7}Sr_{0.3}MnO_3/Yba_2Cu_3O_7/La_{0.7}Sr_{0.3}MnO_3 Trilayers

62%

Przyslupski P., Dybko K., Werner-Malento K., Aleshkevych P., Wojcik M., Sawicki M.

Acta Physica Polonica A

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2010

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vol. 118

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issue 2

313-315

EN

Differential dynamical subgap transport measurements were performed on LSMO/YBCO/LSMO trilayers to probe local evolution of the Andreev bound states which are manifested as the zero bias conductance peak. Dynamical conductivity dI/dV vs. magnetic field measured in current in plane and current perpendicular to plane geometries show nonmonotonic behavior with maximum at about 500 Oe. The shape of the zero bias conductance peak measured in current in plane geometry is sharp, whereas zero bias conductance peak measured in current perpendicular to plane geometry demonstrates V shape. These shapes of the zero bias conductance peak were predicted theoretically for unconventional p-wave spin triplet phase superconductor and superconductor with d-wave symmetry of the order parameter, respectively.

7

Formation of Iron-Containing Clusters in Silica of Predetermined Porosity

52%

Šimkiene I., Baran M., Babonas G., Bendorius R., Rėza A., Szymczak R., Aleshkevych P., Šustavičiūtė R., Tamaševičius R.

Acta Physica Polonica A

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2005

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vol. 107

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issue 2

400-407

EN

Iron-containing nanoparticles and clusters were formed in silica with porosity, which was predetermined by different procedures of sol-gel technology and the chemical composition of precursors. Bulk and layer-type samples of different porosity were synthesized and investigated. The morphology, magnetic, and optical properties were studied to characterize the samples and to analyze the formation of Fe-oxides. Experimental results showed that both Fe_2O_3 and Fe_3O_4 were formed in the samples and that their relative amount was dependent on preparation technology.

8

Thermal Evolution of Magnetic Interactions in Ni Nanowires Embedded in Polycarbonate Membranes by Ferromagnetic Resonance

52%

Ghaddar A., Gieraltowski J., Gloaguen F., Żuberek R., Aleshkevych P., Kazmierczak J., Slawska-Waniewska A., Szymczak H.

Acta Physica Polonica A

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2009

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vol. 116

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issue 6

1039-1043

EN

Ni polycrystalline nanowires with diameters of 50, 80, and 100 nm were electrodeposited in cylindrical pores of track-etched polycarbonate membranes. Their magnetic properties were determined as a function of temperature using ferromagnetic resonance and magnetization measurements. At room temperature, the uniaxial anisotropy is equal to the shape anisotropy whereas an additional contribution is evidenced at low temperature. This additional contribution is attributed to magnetoelastic effects induced in the nanowires due to the different thermal expansion constants of Ni and polycarbonate. The analysis of magnetization processes in Ni nanowire arrays evidenced strong dipolar interactions inside the wires due to the domain structure. The coercive field of the nanowires was shown to be nearly a linear function of the temperature and could be accounted for temperature dependence of the uniaxial anisotropy.

9

Surface Magnetic Anisotropy of Epitaxial La_{0.7}Mn_{1.3}O_{2.84} Thin Films

52%

Aleshkevych P., Baran M., Dyakonov V., Szymczak R., Szymczak H., Baberschke K., Lindner J., Lenz K.

Acta Physica Polonica A

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2006

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vol. 110

|

issue 1

57-70

EN

A spin-wave resonance technique was used to collect information on elementary magnon excitations in high quality epitaxial La_{0.7}Mn_{1.3}O_{2.84} films prepared by dc-magnetron sputtering. It was found that besides bulk spin-wave modes, the spin-wave resonance spectrum includes also the surface spin waves. The value of spin-wave stiffness constant D=156 meV·Å^2 was found. The values of the surface magnetic anisotropy on both surfaces and their angular dependence were determined. The experimentally found spin-wave resonance spectra were explained based on the surface-inhomogeneity model. The effect of surface anisotropy on the spin-wave excitation conditions in epitaxial La_{0.7}Mn_{1.3}O_{2.84} films was investigated. Spin-wave resonance data give an indirect evidence of periodic charge-ordered stripes formation.

10

Ferromagnetism of Narrow-Gap Ge_{1-x-y}Sn_xMn_yTe and Layered In_{1-x}Mn_xSe Semiconductors

42%

Lashkarev G., Sichkovskyi V., Radchenko M., Dmitriev A., Slyn'ko V., Slyn'ko E., Kovalyuk Z., Butorin P., Knoff W., Story T., Szymczak R., Jakieła R., Aleshkevych P., Dobrowolski W.

Acta Physica Polonica A

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2008

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vol. 114

|

issue 5

1219-1227

EN

Magnetic susceptibility, Hall effect and resistivity of narrow-gap Ge_{1-x-y}Sn_xMn_yTe single crystals (x = 0.083÷0.115; y = 0.025÷0.124) were investigated in the temperature range 4.2-300 K revealing a ferromagnetic ordering at T_C ≈ 50 K. Temperature dependence of magnetization indicates a superparamagnetic phase with magnetic clusters arranging in a spin glass state below the freezing temperature T_f. Magnetic structure of InSe ⟨Mn⟩ 2D-ferromagnetic single crystals was studied by SQUID magnetometry, neutron diffraction, secondary ion mass spectroscopy, and wave dispersive spectra. Hysteresis loops of magnetization were observed at least up to 350 K. The cluster model of ferromagnetism is considered. The formation of self-assembled superlattice ferromagnetic InSe:Mn/antiferromagnetic MnSe during growth process and further annealing was established.

Refine search results

EPR in Kagome Staircase Compound Mg_{2.997}Co_{0.003}V_2O_8

Magnon Excitations in Manganites

Geometrically Frustrated Kagome Lattice with Chemical Disorder

Spin-Glass Transition in the RCoGaO_{4} (R=Lu, Yb) Layered Cobaltites

Effect of Chemical Disorder on Geometrically Frustrated Kagome Lattice

Signature of the Spin Triplet Phase in La_{0.7}Sr_{0.3}MnO_3/Yba_2Cu_3O_7/La_{0.7}Sr_{0.3}MnO_3 Trilayers

Formation of Iron-Containing Clusters in Silica of Predetermined Porosity

Thermal Evolution of Magnetic Interactions in Ni Nanowires Embedded in Polycarbonate Membranes by Ferromagnetic Resonance

Surface Magnetic Anisotropy of Epitaxial La_{0.7}Mn_{1.3}O_{2.84} Thin Films

Ferromagnetism of Narrow-Gap Ge_{1-x-y}Sn_xMn_yTe and Layered In_{1-x}Mn_xSe Semiconductors