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See detailMagnetically controlled superconducting weak links
Van de Vondel, J.; Silhanek, Alejandro ULg; Raes, B. et al

in Applied Physics Letters (2009), 95(3),

We have designed and characterized a magnetic template which can be switched between chains of parallel and antiparallel field distribution by applying an in-plane magnetic field. The parallel field ... [more ▼]

We have designed and characterized a magnetic template which can be switched between chains of parallel and antiparallel field distribution by applying an in-plane magnetic field. The parallel field profile creates highly mobile vortex channels in a superconducting film deposited on top, reproducing the behavior of a weak link as evidenced by the presence of Shapiro steps in the current-voltage characteristics under rf excitation. The Josephson coupling can be fully suppressed by changing the field distribution to the antiparallel state. As a result, a reversible ON/OFF switch for magnetically induced weak links has been demonstrated. [less ▲]

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See detailMagnetically supported zeolite adsorbents for effluent treatment
Pramatarova, R.; Gaydardzhiev, Stoyan ULg

in Gaballah, Hager and Solozabal (Ed.) REWAS’99 - Proceedings of the Global Symposium on Recycling, Waste treatment and Clean Technology, San Sebastian, Spain, 2469-2474. (1999)

Zeolite adsorbents packed in magnetic carrier beds have been used for metals removal from synthetic multielemental effluent solution. Prolonged operation of the bed at high mass transfer rates and good ... [more ▼]

Zeolite adsorbents packed in magnetic carrier beds have been used for metals removal from synthetic multielemental effluent solution. Prolonged operation of the bed at high mass transfer rates and good regeneration degree have been achieved. Some of the loaded zeolite samples have been subjected to X-ray mapping for revealing the adsorption mechanism. [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-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 detailMagnetometry of a sample of massive stars in Carina
Nazé, Yaël ULg; Bagnulo, Stefano; Petit, Véronique et al

in Monthly Notices of the Royal Astronomical Society (2012), 423

X-ray surveys of the Carina nebula have revealed a few hard and luminous sources associated with early-type stars. Such unusual characteristics for the high-energy emission may be related to magnetically ... [more ▼]

X-ray surveys of the Carina nebula have revealed a few hard and luminous sources associated with early-type stars. Such unusual characteristics for the high-energy emission may be related to magnetically confined winds. To search for the presence of magnetic fields in these objects, we performed a limited spectropolarimetric survey using the Focal reducer and low dispersion spectrograph (FORS) instrument. The multi-object mode was used, so that a total of 21 OB stars could be investigated during a one-night-long run. A magnetic field was detected in two objects of the sample, with a 6σ significance: Tr16-22 and 13. Such a detection was expected for Tr16-22, as its X-ray emission is too bright, variable and hard, compared to other late-type O or O+OB systems. It is more surprising for Tr16-13, a poorly known star which so far has never shown any peculiar characteristics. Subsequent monitoring is now needed to ascertain the physical properties of these objects and enable a full modelling of their magnetic atmospheres and winds. Based on data collected at ESO under Program ID 386.D-0624A. [less ▲]

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See detailMagnetopause Boundary Normal Analysis at Jupiter and Saturn: Evidence of Kelvin Hemholtz Vorticies
Stauffer, Blake Hughes; Delamere, Peter A; Ma, Xuanye et al

Poster (2013, December 10)

Identification of surface waves and Kelvin Hemholtz (KH) vorticies at the magnetopause boundary at Jupiter and Saturn is critical to understanding interaction between the solar wind and their planetary ... [more ▼]

Identification of surface waves and Kelvin Hemholtz (KH) vorticies at the magnetopause boundary at Jupiter and Saturn is critical to understanding interaction between the solar wind and their planetary magnetospheres. The rapid rotation of those planets coincides with a co-rotating plasma that creates an asymmetry between the formation and evolution of surface waves on either side of the sub-solar point. Minimum variance analysis and other techniques are performed on hundreds of select crossings of Saturn's magnetopause from 2004 to 2012 by the Cassini spacecraft and 47 crossings at Jupiter's magnetopause by the Galileo spacecraft. It is compared to the boundary normals of a simple magnetopause model. The wide range in angular difference between the model and the analysis is evidence of the presence of KH instability vorticies at the magnetopause boundary. Furthermore, boundary crossings from the magnetosheath into the magnetosphere on the dusk flanks are dominated by shallower angles, consistent with MHD simulations of variable shear flows on the dayside magnetopause boundary. [less ▲]

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See detailMagnetosonic modes with a beam of dust or secondary ions
Cramer, N. F.; Verheest, F.; Cattaert, Tom ULg et al

in Physics of Plasmas (2004), 11(10), 4589-4595

Charged dust particles on near-Keplerian orbits in planetary rings drift relative to the corotating background plasma, and this relative streaming may drive dust-modified magnetosonic waves unstable ... [more ▼]

Charged dust particles on near-Keplerian orbits in planetary rings drift relative to the corotating background plasma, and this relative streaming may drive dust-modified magnetosonic waves unstable. Using a magnetofluid model, this situation is revisited, and it is shown that a correct description can be obtained at frequencies and Doppler shifts that are small compared to the electron gyrofrequency. An excellent agreement is reached between the analytical approximation and the numerical solution of the full or reduced dispersion law. A very low-frequency, small wave number beam instability may occur at supermagnetosonic beam velocities of the dust component, but, based on the existing data, is unlikely to play a role in planetary rings. Instability is also found for submagnetosonic speeds, which might be relevant to Saturn's E ring. (C) 2004 American Institute of Physics. [less ▲]

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See detailMagnetospheric dynamics at Jupiter and Saturn
Palmaerts, Benjamin ULg

Speech (2014)

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