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1
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AC Susceptibility Studies of Phase Transitions and Magnetic Relaxation: Conventional, Molecular and Low-Dimensional Magnets

100%
Bałanda M.
Acta Physica Polonica A
|
2013
|
vol. 124
|
issue 6
964-976
EN
The paper presents the review of AC susceptibility measurements in study of magnetic phase transitions and spin dynamics. Examples of several types of phase transitions in conventional and molecular magnets are shown. The phenomenon of magnetic relaxation is briefly ascribed and illustrated with results on relaxation in low-dimensional molecular magnets, such as single molecule magnets, single chain magnets and quasi 1-dimensional systems showing magnetic phase transition to the long-range ordered phase. The following experimental possibilities of the AC technique, which allow to get insight into properties of novel magnetic materials are mentioned: (i) change of the AC field amplitude (in order to distinguish ferro-(ferri) and antiferromagnets); (ii) use of a static field H_{DC} (to conclude on the type of magnetic order and to study the phase diagram); (iii) measurement of nonlinear susceptibilities (to conclude on the type of phase transition); (iv) probing the dependence of both components of susceptibility on frequency of the AC field (to study magnetic relaxation); (v) tests of the DC field effect on the frequency dependence of χ_{AC} (to analyze the possibility of blocking or reentrant spin-glass transition).
2
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Magnetic Investigation of Carbon Coated Co-, Ni- and Fe-Nanoparticles

51%
Makarewicz M., Podsiadły M., Bałanda M.
Acta Physica Polonica A
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2009
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vol. 115
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issue 2
568-571
EN
Carbon coated cobalt-, nickel- and iron-nanoparticles were prepared by chemical method and their structural and magnetic properties were investigated. The samples were synthesized by carburization of the nanocrystalline form of the appropriate metal in CH_4, followed up by the reduction of the obtained carbon deposits. The X-ray diffraction and transmission electron microscopy study revealed carbon coated Co-, Ni- and Fe-nanocapsules of the mean size ca. 50 nm, and a small amount of carbon nanotubes. The measurements of magnetization and AC susceptibility were carried out for samples with different carbon content. A special attention was paid to the low temperature magnetic behavior. Decrease in the saturation moment at T=4.2 K due to the nanosize of the particles was stronger for the samples with higher carbon content, while the coercivity field (610 Oe, 330 Oe and 390 Oe, for Co-, Ni-, and Fe-particles, respectively) was independent of carbon content. From the temperature dependence of AC and DC susceptibility a wide size distribution of the particles and blocking temperature above room temperature could be expected.
3
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Photo-Induced Relaxation of Magnetization in Molecular Magnet

39%
Zieliński P., Tracz P., Podgajny R., Pełka R., Bałanda M., Wasiutyński T., Sieklucka B.
Acta Physica Polonica A
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2007
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vol. 112
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issue S
S-183-S-188
EN
The experimental study of photo-induced magnetization of hybrid molecular magnet containing cobalt(II) and tungsten(V) magnetic centers bridged by 4,4'-bpy and CN^- is presented. The observed increase in magnetization rate is attributed to the defects due to inter-valence transfer between Co^{II}W^V↔ Co^{III}W^{IV}. The time evolution of magnetization is parameterized by the power law rather than exponential function.
4
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Chemical, Magnetic and X-Ray Diffraction Studies of the Sediments from Oil Field in Argentina

39%
Kopeć M., Kąc M., Bałanda M., Budziak A., Kąc S., Perzanowski M., Góra M.
Acta Physica Polonica A
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2012
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vol. 121
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issue 2
566-570
EN
Chemical, magnetic, and phase composition analysis of deposits taken from sedimentation tank from oil plant in Argentina was carried out. Energy dispersive spectroscopy indicates iron as a main sediment component with the site dependent fraction ranging from 11% to 78% (weight percentage). Moreover, large fractions of sulfur (4%-33%), oxygen (8%-28%), calcium (1%-14%), and silicon (1%-11%) were found. The chemical analysis performed with wet chemical methods also indicated Fe as a main component (about 35%), additionally a large fraction ( ≈ 15%) of the sulfur and under 10% fractions of calcium ( ≈ 7%), carbon ( ≈ 6%), and silicon ( ≈ 5%) were found in the sample. The phase composition studies performed using X-ray diffraction showed magnetite - Fe_3O_4, goethite - α-FeOOH, lepidocrocite - γ-FeOOH, siderite - FeCO_3, and iron-sulfur compounds (mackinawite - FeS, stoichiometric FeS, greigite - Fe_3S_4) and other compounds like aragonite - CaCO_3, calcite - CaCO_3, anorthite - CaAl_2Si_2O_8, quartz - SiO_2 and barium sulphate Ba(SO_3)_{0.3}(SO_4)_{0.7}. Studies performed by the Mössbauer spectroscopy, confirmed presence of majority of compounds identified by X-ray diffraction. Magnetic AC susceptibility measurements show that magnetite is a main component of the studied deposit. High concentration of the magnetic compounds deposited in the sedimentation tank points to the advisability to install the magnetic device designed to support water treatment processes, i.e.: flocculation, coagulation, sedimentation, and filtration. This device could simultaneously inhibit microbiological and chemical corrosion.
5
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Magnetic Properties of TbNi_{1-x}Au_xIn Compounds

39%
Bałanda M., Penc B., Baran S., Jaworska-Gołąb T., Arulraj A., Szytuła A.
Acta Physica Polonica A
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2009
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vol. 115
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issue 1
174-177
EN
Polycrystalline samples of TbNi_{1-x}Au_xIn for x = 0.1, 0.2, 0.4, 0.6 and 0.8 were prepared and studied by powder X-ray and neutron diffraction and ac magnetic susceptibility measurements. These compounds crystallize in the hexagonal ZrNiAl-type structure. With increasing Au content a change in the magnetic structure is observed. For x = 0.1, 0.2 and 0.4 the magnetic order is described by the propagation vector k = (1/2, 0, 1/2) while for x = 0.8 by k = (0, 0, 1/2). Between 1.5 K and the Néel temperature the magnetic order is stable.
6
Content available remote

Magnetic Systems at Criticality: Different Signatures of Scaling

27%
Pełka R., Konieczny P., Fitta M., Czapla M., Zieliński P., Bałanda M., Wasiutyński T., Miyazaki Y., Inaba A., Pinkowicz D., Sieklucka B.
Acta Physica Polonica A
|
2013
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vol. 124
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issue 6
977-989
EN
Different aspects of critical behaviour of magnetic materials are presented and discussed. The scaling ideas are shown to arise in the context of purely magnetic properties as well as in that of thermal properties as demonstrated by magnetocaloric effect or combined scaling of excess entropy and order parameter. Two non-standard approaches to scaling phenomena are described. The presented concepts are exemplified by experimental data gathered on four representatives of molecular magnets.
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