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See detailMagnetism and lattice dynamics of FeNCN compared to FeO
Herlitschke, M.; Tchougréeff, A. L.; Soudackov, A. V. et al

in New Journal of Chemistry (2014), 38(10), 4670-4677

Three-dimensional non-oxidic extended frameworks offer the possibility to design novel materials with unique properties, which can be different from their oxide analogues. Here, we present first ... [more ▼]

Three-dimensional non-oxidic extended frameworks offer the possibility to design novel materials with unique properties, which can be different from their oxide analogues. Here, we present first experimental results concerning unusual magnetic properties of FeNCN, investigated using Mössbauer spectroscopy and magnetometry between 5 and 380 K. This study reveals an unconventional behaviour of the magnetic parameters below the Néel temperature of 350 K, i.e., the hyperfine field on iron decreases with decreasing temperature. At room temperature, quadrupole and hyperfine magnetic field interaction energies are comparable in magnitude, which leads to a rare five-line absorption spectrum. We suggest that these features in the hyperfine field are caused by the combination of a small Fermi contact term and a temperature-dependent contribution from the orbital momentum and the dipole term. One additional spectral component is observed, which exhibits a magnetic relaxation behaviour and slows down at low temperatures to yield a sextet. The magnetometry data suggest that the antiferromagnetic FeNCN is rich in structural distortions, which results in a splitting of the field-cooled and zero-field-cooled curves. The lattice dynamics of FeNCN were investigated using nuclear inelastic scattering. The comparison of the obtained data with literature data of iron monoxide reveals very similar iron phonon modes with a small softening and a slightly reduced sound velocity. This journal is © the Partner Organisations 2014. [less ▲]

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See detailMagnetism in U2T2X compounds
Havela, Ladislav; Sechovsky, Vladimir; Svoboda, P. et al

in Journal of Magnetism & Magnetic Materials (1995), 140-144(2), 1367-1368

Magnetic and other electronic properties are presented for the U2T2X compounds (T = late transition metal, X = Sn or In), that crystallize in the tetragonal U3Si2-type structure. They show the formation ... [more ▼]

Magnetic and other electronic properties are presented for the U2T2X compounds (T = late transition metal, X = Sn or In), that crystallize in the tetragonal U3Si2-type structure. They show the formation of 5f magnetic moments and antiferromagnetic ordering in compounds where weak 5f-d hybridization is expected. Near the onset of magnetic ordering strongly enhanced γ-values are found. Neutron-diffraction experiments on U2Pd2Sn and U2Pd2In point to a connection between the mutual coordination of U atoms and the type of magnetic anisotropy [less ▲]

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See detailMagnetism in U2T2X compounds
Havela, Ladislav; Sechovsky, Vladimir; Svoboda, P. et al

Poster (1994, August)

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See detailMagnetization of 2-G Coils and Artificial Bulks
Coombs, Tim; Fagnard, Jean-François ULg; Matsuda, Koichi

in IEEE Transactions on Applied Superconductivity (2014), 24(5), 8201005

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See detailMagneto transport characterization of the Sn-doped TbMnO3 manganites
Pekala, Marek; Drozd, V.; Fagnard, Jean-François ULg et al

in Journal of Alloys & Compounds (2009), 467(1-2), 35-40

The structural, magnetic and electrical transport properties of the Sn-doped TbMnO3 manganites are studied by X-ray diffraction, ac susceptibility, dc magnetization and electrical resistivity measurements ... [more ▼]

The structural, magnetic and electrical transport properties of the Sn-doped TbMnO3 manganites are studied by X-ray diffraction, ac susceptibility, dc magnetization and electrical resistivity measurements. The Sn doping into the Tb and Mn sites of TbMnO3 compresses the unit cell and changes parameters of the antiferromagnetic phase whereas the magnetic moment of Mn are only weakly affected. The electrical resistivity of doped manganites is reduced and the activation energy EA is determined for the thermally activated conduction. [less ▲]

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See detailMagneto-optical trapping of iron atoms
Crauwels, Justine ULg; Huet, Nicolas ULg; Krins, Stéphanie ULg et al

in Belgian Physical Society Magazine (2016), 1

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See detailMagneto-optical trapping of iron atoms
Crauwels, Justine ULg; Huet, Nicolas ULg; Krins, Stéphanie ULg et al

Poster (2015, May 13)

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See detailMagneto-thermal coupling simulations -- Application to the SSM processing of steels
Rassili, A.; Geuzaine, Christophe ULg; Dular, Patrick ULg et al

in Proceedings of the 5th International Workshop on Electric and Magnetic Fields, EMF 2000 (2000)

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See detailMagneto-thermal phenomena in bulk high temperature superconductors subjected to applied AC magnetic fields
Vanderbemden, Philippe ULg; Laurent, Philippe ULg; Fagnard, Jean-François ULg et al

in Superconductor Science and Technology (2010), 23

In the present work we study, both theoretically and experimentally, the temperature increase in a bulk high temperature superconductor subjected to applied AC magnetic fields of large amplitude. We ... [more ▼]

In the present work we study, both theoretically and experimentally, the temperature increase in a bulk high temperature superconductor subjected to applied AC magnetic fields of large amplitude. We calculate analytically the equilibrium temperatures of the bulk sample as a function of the experimental parameters using a simple critical state model for an infinitely long type-II superconducting slab or cylinder. The results show the existence of a limit heat transfer coefficient (AUlim) separating two thermal regimes with different characteristics. The theoretical analysis predicts a ‘forbidden’ temperature window within which the temperature of the superconductor can never stabilize when the heat transfer coefficient is small. In addition, we determine analytical expressions for two threshold fields Htr1 and Htr2 characterizing the importance of magneto-thermal effects and show that a thermal runaway always occurs when the field amplitude is larger than Htr2. The theoretical predictions of the temperature evolution of the bulk sample during a self-heating process agree well with the experimental data. The simple analytical study presented in this paper enables order of magnitude thermal effects to be estimated for simple superconductor geometries under applied AC magnetic fields and can be used to predict the influence of experimental parameters on the self-heating characteristics of bulk type-II superconductors. [less ▲]

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See detailMagneto-transport characterization of Dy123 monodomain superconductors
Pekala, Marek; Mucha, Jan ULg; Vanderbemden, Philippe ULg et al

in Applied Physics A : Materials Science & Processing (2005), 81(5), 1001-1007

We consider textured materials of the DyBa2Cu3O7 type seeded with a Nd123 seed as initiator. They are grown with an excess 20% Dy211 phase on a Dy2O3 substrate. We report chemical characterization ... [more ▼]

We consider textured materials of the DyBa2Cu3O7 type seeded with a Nd123 seed as initiator. They are grown with an excess 20% Dy211 phase on a Dy2O3 substrate. We report chemical characterization, electrical resistivity, thermoelectric power and thermal conductivity over a broad temperature range as a function of an applied magnetic field up to 6 T. We show that specific features appear in the magneto-thermal transport properties, different in these materials from those found in single crystals and polycrystalline samples. We propose that two vortex regimes can be distinguished in the mixed phase, due to the intrinsic microstructure. We calculate the viscosity, entropy and figure of merit of the samples. [less ▲]

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See detailMagneto-transport study of nb-doped Bi/Pb2223 superconductor
Pekala, Marek; Mucha, Jan ULg; Cloots, Rudi ULg et al

in Physica C: Superconductivity (2003), 387(1-2), 191-197

The magneto-transport properties of Bi1.5Pb0.4Nb0.1Sr2Ca2Cu3O10-x polycrystalline, superconducting ceramic are reported. The material was found to be chemically homogeneous and partially textured. The ... [more ▼]

The magneto-transport properties of Bi1.5Pb0.4Nb0.1Sr2Ca2Cu3O10-x polycrystalline, superconducting ceramic are reported. The material was found to be chemically homogeneous and partially textured. The mixed state properties were investigated by measuring the electrical resistivity, longitudinal and transverse (Nernst effect) thermoelectric power, and thermal conductivity. The magnetization and AC susceptibility measurements were also performed. The variation of these characteristics for magnetic fields up to 5 T are discussed and compared to those of the zero field case. The transport entropy and thermal Hall angle are extracted and quantitatively compared to previously reported data of closely related systems. (C) 2003 Elsevier Science B.V. All rights reserved. [less ▲]

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See detailMagnetocaloric and transport study of poly- and nanocrystalline composite manganites La0.7Ca0.3MnO3/La0.8Sr0.2MnO3
Pekala, M; Pekala, K; Drozd, V et al

in Journal of Applied Physics (2012), 112

Magnetocaloric and transport properties are reported for novel poly- and nanocrystalline double composite manganites, La0.8Sr0.2MnO3/La0.7Ca0.3MnO3, prepared by the sol-gel method. Magnetic field ... [more ▼]

Magnetocaloric and transport properties are reported for novel poly- and nanocrystalline double composite manganites, La0.8Sr0.2MnO3/La0.7Ca0.3MnO3, prepared by the sol-gel method. Magnetic field dependence of magnetic entropy change is found to be stronger for the nano- than the polycrystalline composite. The remarkable broadening of the temperature interval, where the magnetocaloric effect occurs in poly- and nanocrystalline composites, causes the relative cooling power (RCP(S)) of the nanocrystalline composite to be reduced by only 10% compared to the Sr based polycrystalline phase. The RCP(S) of the polycrystalline composite becomes remarkably enhanced. The low temperature magnetoresistance is enhanced by 5% for the nanostructured composite. © 2012 American Institute of Physics [less ▲]

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See detailMagnetocaloric effect and magnetic properties of Tb0.9Sn0.1MnO3
Fabris, Frederik Wolff; Pekala, Marek; Drozd, V. et al

in Journal of Applied Physics (2007), 101(10), 103904

The magnetocaloric effect in magnetic materials is of great interest nowadays. In this article we present an investigation about the magnetic properties near the magnetic transition in a polycrystalline ... [more ▼]

The magnetocaloric effect in magnetic materials is of great interest nowadays. In this article we present an investigation about the magnetic properties near the magnetic transition in a polycrystalline sample of a manganite Tb0.9Sn0.1MnO3. Particularly, we are interested in describing the nature of the magnetic interactions and the magnetocaloric effect in this compound. The temperature dependence of the magnetization was measured to determine the characteristics of the magnetic transition and the magnetic entropy change was calculated from magnetization curves at different temperatures. The magnetic solid is paramagnetic at high temperatures. We observe a dominant antiferromagnetic interaction below T-n=38 K for low applied magnetic fields; the presence of Sn doping in this compound decreases the Neel temperature of the pure TbMnO3 system. A drastic increase in the magnetization as a function of temperature near the magnetic transition suggests a strong magnetocaloric effect. We found a large magnetic entropy change Delta S-M(T) of about -4 J/kg K at µ0H=3 T. We believe that the magnetic entropy change is associated with the magnetic transition and we interpret it as due to the coupling between the magnetic field and the spin ordering. This relatively large value and broad temperature interval (about 35 K) of the magnetocaloric effect make the present compound a promising candidate for magnetic refrigerators at low temperatures. (c) 2007 American Institute of Physics. [less ▲]

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See detailMagnetocaloric effect in La0.75Sr0.25MnO3 manganite
Pekala, M.; Pekala, K.; Drozd, V. et al

in Journal of Magnetism & Magnetic Materials (2010), 322(21), 3460-3463

The polycrystalline manganite La0.75Sr0.25MnO3 prepared by an alternative carbonate precipitation route reveals the rhombohedral perovskite structure. Magnetization isotherms measured up to 2 T are used ... [more ▼]

The polycrystalline manganite La0.75Sr0.25MnO3 prepared by an alternative carbonate precipitation route reveals the rhombohedral perovskite structure. Magnetization isotherms measured up to 2 T are used to determine Curie temperature of 332 K by means of Arrott plot. Maximum of magnetic entropy change is found at Curie temperature. The relative cooling power equal to 64 J/kg for 1.5 T magnetic field, is superior as compared to the manganite with the same chemical composition from the sol–gel method. [less ▲]

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See detailMagnetocaloric effect in nano- and polycrystalline manganite La0.7Ca0.3MnO3
Pekala, Marek; Drozd, V.; Fagnard, Jean-François ULg et al

in Applied Physics A : Materials Science & Processing (2008), 90(2), 237-241

La0.7Ca0.3MnO3 samples were prepared in nano- and polycrystalline forms by the sol-gel and solid state reaction methods, respectively, and structurally characterized by synchrotron X-ray diffraction. The ... [more ▼]

La0.7Ca0.3MnO3 samples were prepared in nano- and polycrystalline forms by the sol-gel and solid state reaction methods, respectively, and structurally characterized by synchrotron X-ray diffraction. The magnetic properties determined by ac susceptibility and dc magnetization measurements are discussed. The magnetocaloric effect in this nanocrystalline manganite is spread over a broader temperature interval than in the polycrystalline case. The relative cooling power of the poly- and nanocrystalline manganites is used to evaluate a possible application for magnetic cooling below room temperature. [less ▲]

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See detailMagnetocaloric effect in nano- and polycrystalline manganites La0.5Ca0.5MnO3
Pekala, Marek; Drozd, Vadym; Fagnard, Jean-François ULg et al

in Journal of Alloys & Compounds (2010), 507

Structure, magnetic and magnetocaloric properties of poly- and nanocrystalline La0.5Ca0.5MnO3 manganites prepared by the citrate sol–gel method are studied in a broad temperature range. The Arrott plots ... [more ▼]

Structure, magnetic and magnetocaloric properties of poly- and nanocrystalline La0.5Ca0.5MnO3 manganites prepared by the citrate sol–gel method are studied in a broad temperature range. The Arrott plots show that the phase transition is of the second order. The cooling efficiency of 93–97 J/kg is found for the poly- and nanocrystalline samples. The relatively weaker magnetocaloric effect in nanocrystalline La0.5Ca0.5MnO3 is spread over temperature range almost three times broader than for the polycrystalline one. Charge ordering effects decay in manganites with grain sizes below 150 nm. [less ▲]

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See detailMagnetocaloric effect of monovalent K doped manganites Pr0.6Sr0.4−xKxMnO3 (x=0 to 0.2)
Thaljaoui, R.; Boujelben, W.; Pękała, M. et al

in Journal of Magnetism and Magnetic Materials (2014), 352(0), 6-12

Magnetic and magnetocaloric properties are reported for polycrystalline monovalent potassium doped manganites Pr0.6Sr0.4−xKxMnO3 (x=0, 0.05, 0.1, 0.15 and 0.2) crystallized in orthorhombic structure with ... [more ▼]

Magnetic and magnetocaloric properties are reported for polycrystalline monovalent potassium doped manganites Pr0.6Sr0.4−xKxMnO3 (x=0, 0.05, 0.1, 0.15 and 0.2) crystallized in orthorhombic structure with Pnma space group. The increasing K content shifts the paramagnetic to ferromagnetic transition temperature from 310 K for x=0 to 269 K for x=0.2. The magnetic entropy change under magnetic field variation of 2 T is found to be 1.95, 3.09, 2.89, 3.05 and 3.2 J/kgK for x varying from 0 to 0.2, respectively. The highest relative cooling power of 102 J/kg is observed for the undoped sample. The sensitivity of magnetic entropy change to magnetic field is estimated by a local N(T) exponent exhibiting the characteristic temperature variation. Phenomenological universal curves of entropy change and Arrott plots confirm the second order phase transition. [less ▲]

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See detailMagnetocaloric Properties of Zinc-Nickel Ferrites Around Room Temperature
El Maalam, Khadija; Fkhar, lahcen; Mohammed, Hamedoun et al

in Journal of Superconductivity and Novel Magnetism (2017)

In this paper, structural, magnetic, and magnetocaloric properties of zinc-doped nickel ferrite, Zn1−xNixFe2O4 (x = 0.3 and 0.4) were investigated. The samples were prepared using solid-state reaction. X ... [more ▼]

In this paper, structural, magnetic, and magnetocaloric properties of zinc-doped nickel ferrite, Zn1−xNixFe2O4 (x = 0.3 and 0.4) were investigated. The samples were prepared using solid-state reaction. X-ray diffraction (XRD) and magnetization measurements were performed to study crystallographic structure and magnetic properties. For a magnetic field changing from 0 to 5 T, the corresponding isothermal entropy change was found to be near 1.4 J/kg K for both samples. The decreasing of Ni content from x = 0.4 to 0.3, enables to shift the Curie temperature of Zn1−xNixFe2O4 from 450 K toward (325 K). As main results, it was found that the relative cooling power (RCP) could be significantly enhanced by changing Ni concentration in Zn1−xNixFe2O4 (505 J/kg (for x = 0.3) and 670 J/kg (for x = 0.4)), which is considered as a recommended parameter for a wide temperature range in magnetic refrigeration application. Our finding should inspire and open new ways for the enhancement of the magnetocaloric effect in spinel ferrite-based materials. [less ▲]

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See detailMagnetocapillary self-assemblies: Swimming and micromanipulation
Grosjean, Galien ULg; Hubert, Maxime ULg; Lagubeau, Guillaume et al

Poster (2016, July)

Floating magnetic particles can self-assemble into structures, by a combination of a magnetic dipole-dipole interaction and an attraction due to the interfacial deformation. These structures are ... [more ▼]

Floating magnetic particles can self-assemble into structures, by a combination of a magnetic dipole-dipole interaction and an attraction due to the interfacial deformation. These structures are periodically deformed in a non reciprocal way using magnetic fields, which leads to controllable low Reynolds number locomotion. Such microswimmers provide a basis for micromanipulation applications such as transport of micro-objects, local mixing of fluids or surface cleaning. [less ▲]

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See detailThe Magnetodiscs and Aurorae of Giant Planets
Szego, Karoly; Achilleos, Nicholas; Arridge, Chris et al

Book published by Springer Science & Business Media B.V. - Previously published in Space Science Reviews, Volume 187, Issues 1-4, 2015 (2016)

This volume contains the reports discussed during the Workshop “Giant Planet Magne- todiscs and Aurorae” held 26–30 November 2012, at the International Space Science Insti- tute, organised together with ... [more ▼]

This volume contains the reports discussed during the Workshop “Giant Planet Magne- todiscs and Aurorae” held 26–30 November 2012, at the International Space Science Insti- tute, organised together with the Europlanet project, supported by FP7 (Grant No. 228319). Magnetodiscs are large current sheets surrounding Jupiter and Saturn (also Uranus and Neptune) that are filled with plasma principally originating in the natural satellites of these worlds. They are also solar system analogues for astrophysical discs. Magnetodiscs are spe- cial features of the fast rotating giant planets, a special feature of rotationally driven magne- tospheres. Their structure is modified by variability in their plasma sources and by the solar wind. Auroral signatures in the optical and radio wavebands allow a diagnostic of these dynamical processes and enable the visualisation of these large plasma and field structures.The objective of this workshop was to address outstanding issues in the structure and dynamics of magnetodiscs using a comparative approach (see details under topics). More specifically, we aimed to review current understanding of magnetodiscs and auroral re- sponses to magnetodisc dynamics; characterise and understand radial plasma transport in magnetodiscs; determine how magnetic reconnection works in magnetodiscs, and describe the effects on plasma transport; describe the associated auroral responses to internal and ex- ternal magnetospheric processes; characterise how the solar wind influences magnetodiscs and the auroral responses to solar wind-driven dynamics; characterise the spectral and spa- tial properties of auroral emissions produced by magnetodisc dynamics; answer the ques- tion of whether there are significant differences between solar wind- and internally-driven dynamics; and determine the sources of local-time asymmetries in magnetodiscs. This volume is a unique synthesis of all aspects of the giant magnetospheres and their aurorae; it provides an interdisciplinary approach to understanding the coupled system from the solar wind to the atmosphere; it combines the latest observations with current theory and models; and it also contains sufficient breadth for students of magnetospheric and space physics to use as a reference for future research. [less ▲]

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