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See detailMagnetic and electronic ground states of B-site-substituted LaMnO3: from antiferromagnetism to ferromagnetism
Vertruyen, Bénédicte ULg; Flahaut, Delphine; Hebert, Sylvie et al

in Journal of Magnetism & Magnetic Materials (2004), 280(1), 75-83

We report about the physical properties of samples obtained by different substitutions on the Mn site of LaMnO3: LaMn0.85Ni0.15O3, LaMn0.85Ga0.15O3 and LaMn0.5Ga0.5O3. It is well known that the ... [more ▼]

We report about the physical properties of samples obtained by different substitutions on the Mn site of LaMnO3: LaMn0.85Ni0.15O3, LaMn0.85Ga0.15O3 and LaMn0.5Ga0.5O3. It is well known that the antiferromagnetic orbitally ordered ground state of LaMnO3 is easily destroyed to give way to ferromagnetism. However, this ferromagnetic behaviour can result from several mechanisms: depending on the nature of the substituting cation and on the substitution level, the physical properties derived from a complex interplay between exchange interactions, orbital ordering and Jahn-Teller distortion. As a result, there are noticeable differences between the physical properties of the different samples, even though all three samples display a ferromagnetic component in zero applied magnetic field. In this paper we compare the crystallographic, electrical and magnetic properties of these samples, with a special attention for the AC susceptibility behaviour. (C) 2004 Elsevier B.V. All rights reserved. [less ▲]

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See detailMagnetic and electronic properties of Eu4Sr4Ga16Ge30
Woods, G. T.; Marti; Beekman, M. et al

in Physical Review b (2006), 73(17),

Magnetization, static and ac magnetic susceptibility, nuclear forward scattering, and electrical resistivity measurements have been performed on polycrystalline Eu4Sr4Ga16Ge30, a type I clathrate that has ... [more ▼]

Magnetization, static and ac magnetic susceptibility, nuclear forward scattering, and electrical resistivity measurements have been performed on polycrystalline Eu4Sr4Ga16Ge30, a type I clathrate that has divalent strontium and europium ions encapsulated within a Ga-Ge framework. These data are compared with those of type I clathrates Eu8Ga16Ge30 and Eu6Sr2Ga16Ge30. The ferromagnetic ordering of these Eu-containing clathrates is substantially altered by the incorporation of strontium, as compared to Eu8Ga16Ge30. Ferromagnetism, accompanied by a relatively large negative magnetoresistance, is observed below 15 and 20 K in Eu4Sr4Ga16Ge30 and Eu6Sr2Ga16Ge30, respectively. An effective magnetic moment of 7.83 mu(B) per Eu ion is observed above 30 K for Eu4Sr4Ga16Ge30, a moment which is close to the free-ion moment of 7.94 mu(B) per europium(II) ion. [less ▲]

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See detailMagnetic and mossbauer spectral study of ErFe11Ti and ErFe11TiH
Piquer, C.; Hermann, Raphaël ULg; Grandjean, Fernande ULg et al

in Journal of Applied Physics (2003), 93(6), 3414-3421

X-ray diffraction, isothermal magnetization at 5 and 300 K, ac magnetic susceptibility measurements between 5 and 200 K, and iron-57 Mossbauer spectral measurements between 4.2 and 295 K have been carried ... [more ▼]

X-ray diffraction, isothermal magnetization at 5 and 300 K, ac magnetic susceptibility measurements between 5 and 200 K, and iron-57 Mossbauer spectral measurements between 4.2 and 295 K have been carried out on ErFe11Ti and ErFe11TiH. Hydrogen uptake has been measured by gravimetric analysis and the insertion of hydrogen into ErFe11Ti increases its magnetization, magnetic hyperfine fields, and isomer shifts as a result of the associated lattice expansion. Peaks and steplike changes in both the real and imaginary components of the ac magnetic susceptibility are observed at similar to50 and 40 K for ErFe11Ti and ErFe11TiH, respectively, and are assigned to spin-reorientation transitions resulting from the temperature dependence of the sixth-order Stevens crystal-field term of erbium. The Mossbauer spectra have been analyzed with a model which considers both these spin reorientations and the distribution of titanium atoms in the near-neighbor environment of the three crystallographically distinct iron sites. The assignment and the temperature dependencies of the hyperfine fields and isomer shifts are in complete agreement with the Wigner-Seitz cell analysis of the three iron sites in ErFe11Ti and ErFe11TiH. The changes in the hyperfine field and isomer shift with the number of titanium near neighbors of the three iron sites are in agreement with the values observed for related titanium-iron intermetallic compounds. (C) 2003 American Institute of Physics. [less ▲]

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See detailA Magnetic and Mössbauer Spectral Study of Several Na-Mn-Fe-bearing Alluaudites
Long, Gary J.; Hautot, Dimitri; Hatert, Frédéric ULg et al

Poster (2001)

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See detailA magnetic and Mossbauer spectral study of TbFe11Ti and TbFe11TiH
Piquer, C.; Hermann, Raphaël ULg; Grandjean, François-Xavier ULg et al

in Journal of Physics : Condensed Matter (2003), 15(43), 7395-7409

Magnetic and iron-57 Mossbauer spectral measurements between 4.2 and 640 K have been carried out on TbFe11Ti and TbFe11TiH. The insertion of hydrogen into TbFe11Ti form TbFe11TiH increases its ordering ... [more ▼]

Magnetic and iron-57 Mossbauer spectral measurements between 4.2 and 640 K have been carried out on TbFe11Ti and TbFe11TiH. The insertion of hydrogen into TbFe11Ti form TbFe11TiH increases its ordering temperature, magnetization, magnetic hyperfine fields, and isomer shifts as a result of lattice expansion. Further, the insertion of hydrogen reinforces the basal magnetic anisotropy of the terbium sublattice and, as is shown by ac susceptibility measurements and thermomagnetic analysis, the spin reorientation observed in TbFe11Ti at 338 K disappears in TbFe11TiH. The Mossbauer spectra have been analysed with a model that considers both the easy magnetization direction and the distribution of titanium atoms in the near-neighbour environment of the three crystallographically distinct iron sites. The assignment and the temperature dependencies of the hyperfine fields and isomer shifts are in complete agreement with a Wigner-Seitz cell analysis of the three iron sites in RFe11Ti and RFe11TiH, where R is a rare-earth element. A complete analysis of the quadrupole interactions in both magnetic phases and in the paramagnetic phase of TbFe11Ti supports the Mossbauer spectral analysis, and indicates that in the basal magnetic phase the iron magnetic moments are oriented along the equivalent [100] and [010] directions of the unit cell. [less ▲]

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See detailMagnetic and transport measurements on melt-textured DyBCO single domains
Vanderbemden, Philippe ULg; Misson, Vincent; Ausloos, Marcel ULg et al

in Physica C: Superconductivity (2002), 372(Part 2), 1225-1228

In this communication we report critical current measurements of melt processed DyBa2Cu3O7-x samples determined by several measuring techniques. First the material was characterized by AC susceptibility ... [more ▼]

In this communication we report critical current measurements of melt processed DyBa2Cu3O7-x samples determined by several measuring techniques. First the material was characterized by AC susceptibility and DC magnetization. The results are characteristic of good quality melt-processed (RE)BCO material with T-c = 89 K and Jc(77 K, 1 T) = 10^4 A/cm^2. Next, pulsed currents were used in order to determine both I-V curves and transport critical currents. The origin of the discrepancy between transport and magnetic data has been discussed. The results point out significant local variations of the critical current density throughout the single domain. (C) 2002 Elsevier Science B.V. All rights reserved. [less ▲]

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See detailMagnetic and transport properties investigation of rare-earth compounds with orthorhombic structures
Lovchinov, V.; Apostolov, A.; Dimitrov, D. et al

in Journal of Optoelectronics and Advanced Materials [= JOAM] (2007), 9(2), 460-463

The structural, magnetic, magnetoelectric, and ferroelectric properties of a series of monocrystals with perovskite structures have been examined. The investigations were carried out in the temperature ... [more ▼]

The structural, magnetic, magnetoelectric, and ferroelectric properties of a series of monocrystals with perovskite structures have been examined. The investigations were carried out in the temperature range 2-800 K and at magnetic fields up to 14 T. The existence of giant magnetoresistance (GMR) for some samples, a giant magnetostiction effect for others and the presence of multiphase ferroelectric states were demonstrated. Various possibilities for practical applications are discussed. [less ▲]

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See detailMagnetic and transport properties of HoMnO3 monocrystals
Radulov, Iliya; Lovchinov, Vassil; Dimitrov, Dimitar et al

in Journal of Optoelectronics and Advanced Materials [= JOAM] (2009), 11

This paper presents results from measurements of the magnetization, specific heat and dielectric constant, and their temperature and magnetic field dependence, for HoMnO3 single crystals. The results are ... [more ▼]

This paper presents results from measurements of the magnetization, specific heat and dielectric constant, and their temperature and magnetic field dependence, for HoMnO3 single crystals. The results are discussed in the framework of existing data on magnetic symmetries and the interactions between the Mn-spins, the rare earth moments, and the lattice. From the resulting data, the magnetic phase diagram of HoMnO3 was built. [less ▲]

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See detailMagnetic anisotropy of U2Pd2In
Prokes, Karel; Nakotte, Heinz; Havela, Ladislav et al

in Physica B: Condensed Matter (1996), 223-224

Magnetic susceptibility studies of the U2Pd2In single crystal show that in the paramagnetic state larger χ-values are found for field along the basal plane than along the c-axis. However, below TN = 37 K ... [more ▼]

Magnetic susceptibility studies of the U2Pd2In single crystal show that in the paramagnetic state larger χ-values are found for field along the basal plane than along the c-axis. However, below TN = 37 K, where U-moments form a non-collinear magnetic structure within the basal plane, a cross-over of the two χ-branches occurs. The single crystal results may explain the origin of the exotic magnetization results obtained on powder samples. [less ▲]

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See detailMagnetic behaviour of soft ferromagnetic alloys attached to bulk (RE)BCO superconductors
Philippe, Matthieu ULg; Fagnard, Jean-François ULg; Dennis, Anthony et al

Poster (2012, October)

Bulk (RE)BCO materials can be used potentially as powerful permanent magnets. The magnetic field distribution around a bulk HTS magnet, however, is strongly non-uniform (conic profile predicted by the ... [more ▼]

Bulk (RE)BCO materials can be used potentially as powerful permanent magnets. The magnetic field distribution around a bulk HTS magnet, however, is strongly non-uniform (conic profile predicted by the Bean model) compared to the rather flatter distribution around a ferromagnet. In the present work, we study how FeNi soft ferromagnetic alloys of different shapes can be combined with (RE)BCO bulk superconductors to improve the distribution of trapped field or its average value at the surface of the bulk sample. The FeNi ferromagnetic alloys are machined into pieces of various shapes (e.g. cylinder, cone) attached to the bottom surface of the bulk HTS disks. The magnetic properties of each ferromagnetic/superconductor (F/S) assembly are measured under axial magnetic field at 77 K. Small coils and Hall probe mappings provide the average magnetization and field distribution respectively. The results are compared to the intrinsic magnetic hysteresis curves of the magnetic alloys and of the superconductor. Measurements of the average magnetization show that the effects of the ferromagnetic alloys depend mainly on the volume of the ferromagnet and add up to the effect of the superconductor. However, at constant ferromagnetic volume, the shape of the ferromagnetic piece is found to influence the magnetic field penetration and distribution against the top surface of the superconductor. [less ▲]

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See detailMagnetic characterisation of large grain, bulk Y–Ba–Cu–O superconductor–soft ferromagnetic alloy hybrid structures
Philippe, Matthieu ULg; Fagnard, Jean-François ULg; Kirsch, Sébastien ULg et al

in Physica C: Superconductivity (2014), 502

Large grain, bulk Y–Ba–Cu–O (YBCO) high temperature superconductors (HTS) have significant potential for use in a variety of practical applications that incorporate powerful quasi-permanent magnets. In ... [more ▼]

Large grain, bulk Y–Ba–Cu–O (YBCO) high temperature superconductors (HTS) have significant potential for use in a variety of practical applications that incorporate powerful quasi-permanent magnets. In the present work, we investigate how the trapped field of such magnets can be improved by combining bulk YBCO with a soft FeNi, ferromagnetic alloy. This involves machining the alloy into components of various shapes, such as cylinders and rings, which are attached subsequently to the top surface of a solid, bulk HTS cylinder. The effect of these modifications on the magnetic hysteresis curve and trapped field of the bulk superconductor at 77 K are then studied using pick-up coil and Hall probe measurements. The experimental data are compared to finite element modelling of the magnetic flux distribution using Campbell’s algorithm. Initially we establish the validity of the technique involving pick-up coils wrapped around the bulk superconductor to obtain its magnetic hysteresis curve in a non-destructive way and highlight the difference between the measured signal and the true magnetization of the sample. We then consider the properties of hybrid ferromagnet/superconductor (F/S) structures. Hall probe measurements, together with the results of the model, establish that flux lines curve outwards through the ferromagnet, which acts, effectively, like a magnetic short circuit. Magnetic hysteresis curves show that the effects of the superconductor and the ferromagnet simply add when the ferromagnet is saturated fully by the applied field. The trapped field of the hybrid structure is always larger than that of the superconductor alone below this saturation level, and especially when the applied field is removed. The results of the study show further that the beneficial effects on the trapped field are enhanced when the ferromagnet covers the entire surface of the superconductor for different ferromagnetic components of various shapes and fixed volume. [less ▲]

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See detailMagnetic confinement of the superconducting condensate in superconductor-ferromagnet hybrid composites
Gillijns, W.; Aladyshkin, A Yu; Silhanek, Alejandro ULg et al

in Physical Review. B : Condensed Matter (2007), 76(6),

The influence of an inhomogeneous magnetic field on the magnetoresistance of thin Al films, used in different superconductor-ferromagnet hybrids, has been investigated. Two contrasting magnetic textures ... [more ▼]

The influence of an inhomogeneous magnetic field on the magnetoresistance of thin Al films, used in different superconductor-ferromagnet hybrids, has been investigated. Two contrasting magnetic textures with out-of-plane magnetization are explored: namely, (i) a plain film in a multidomain state and (ii) an array of microsized dots. The stray fields of the ferromagnetic structures confine the superconducting condensate and, accordingly, modify the condition for the nucleation of superconductivity. By switching between different magnetic states of the ferromagnet, this confinement can be tuned at will, thereby reversibly changing the dependence of the critical temperature T-c on an external magnetic field H. In particular, continuous evolution from a conventional linear T-c(H) dependence with a single maximum to a reentrant superconducting phase boundary with multiple T-c peaks has been demonstrated. [less ▲]

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See detailMagnetic diffusion-limited aggregation
Vandewalle, Nicolas ULg; Ausloos, Marcel ULg

in Physical Review. E : Statistical Physics, Plasmas, Fluids, and Related Interdisciplinary Topics (1995), 51(1), 597-603

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See detailMagnetic Eden model
Ausloos, Marcel ULg; Vandewalle, Nicolas ULg; Cloots, Rudi ULg

in Europhysics Letters [=EPL] (1993), 24(8), 629-634

We introduce the <<Magnetic Eden Model(s)>>. It consists in the usual Eden growth model(s), but allowing for the elements of the growth to have an extra degree of freedom (a <<spin>>). The growth is ... [more ▼]

We introduce the <<Magnetic Eden Model(s)>>. It consists in the usual Eden growth model(s), but allowing for the elements of the growth to have an extra degree of freedom (a <<spin>>). The growth is controlled by a condition depending on the <<magnetic state>> of the perimeter (through some <<spin coupling>>) and an external parameter, the <<magnetic field>>. Even though these words seem to refer to some <<energetic condition>> the growth model is of purely kinetic origin. This is demonstrated by exactly solving the 1-dimensional growth model for a semi-open chain, and, e.g. finding the correlation functions. In two-dimensions, simulations of clusters lead us to show that the perimeter growth exponent is coupling dependent. We show the morphologies of growth clusters on a <<phase diagram>> and indicate the <<physical origin>> and transition(s) between compact and lacunar clusters. [less ▲]

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See detailMagnetic fabrics in jotunite dykes from the Late-Proterozoic Rogaland anorthosite province (SW Norway)
Bolle, Olivier ULg; Besse, Michal; Diot, Hervé

in Geophysical Research Abstracts (2005), 7

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See detailMagnetic fabrics in the Holum granite (Vest-Agder, southernmost Norway): implications for the late evolution of the Sveconorwegian (Grenvillian) orogen of SW Scandinavia
Bolle, Olivier ULg; Diot, Hervé; Trindade, Ricardo I.F.

in Precambrian Research (2003), 121(3-4), 221-249

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