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A highly topical set of materials are those ABO3 perovskite oxides, in which multiferroicity is chemically engineered by placing ferroelectrically and magnetically active cations in A- and B-site, respectively. This is the case of the BiFeO3 and BiMnO3 perovskites, and also of the solid solutions they form with PbTiO3. Interest in these binary systems is fostered by the presence of distinctive morphotropic phase boundaries (MPBs), multiferroic in the case of BiFeO3-PbTiO3, for which a high magnetoelectric response has been anticipated. Here, new compositions belonging to the ternary system BiFeO3-BiMnO3-PbTiO3, and specifically along the line that joins the former MPBs, have been prepared by mechanosynthesis to accomplish a thorough analysis of their multiferroic nature. Nanocrystalline powders with a perovskite-type structure were obtained in the entire range of compositions, which all exhibited polymorphic phase coexistence allowing a line of MPBs to be established. The variation of the perovskite structural characteristics along this line has been defined, and correlated with those of the magnetic and electrical properties. A set of novel and promising multiferroic materials have been found for BiFeO3 rich compositions., This work has been founded by the Spanish MINECO (MAT2011-23709). C.M.F-P and H.A. thanks financial support by MINECO (BES 2012-053017) and Ramón y Cajal Programme, respectively. Collaboration between ICMM and ISCR was framed within the COST Action MP0904 SIMUFER.

Magnetic properties of carbon nanotubes (CNT) obtained by plasma-enhanced chemical vapour deposition (PECVD) have been studied. The growth of these nanotubes has been activated from Ni catalyst nanoparticles. Samples consist of Ni nanoparticles encapsulated at the tip of vertically aligned multiwalled carbon nanotubes (VACNTs) forming an homogeneous and dense large area monolayer of isolated (non-contacting) nanoparticles. The magnetic characterisation has been performed in the temperature range of 5-300 K with magnetic fields up to 9 T. The results show that the wide size range (30-180 nm) of the particles originates the coexistence of blocked and superparamagnetic particles and leads to the strong ferromagnetic behaviour of the whole assembly. The coercivity decreases monotonically with increasing temperature and the value for the intrinsic coercivity is 225 Oe. The encapsulation of Ni nanoparticles by VACNTs preserves them from aggregation. This makes possible to tune the coercivity by controlling size distribution of particle monolayers. © 2010 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim. This work was supported in part by the University of Oviedo under Grant No. UNOV-08-MA-100 and by the Spanish MEC through grant Ref. MAT2008-06784. Projects CSD2006-12 and DPI2006-03070 of the Spainsh MEDU and the Generalitat de Catalunya (project No. SGR2005-00666). The authors thank Serveis Cientifico-Tècnics of the Universitat de Barcelona (SCT-UB) for measurement facilities.

We describe the preparation, crystal structure determination, magnetic and transport properties of two novel Mn-containing perovskites, with a different electronic configuration for Mn atoms located in B site. Ca3Mn 3+ 2WO9 and Ca3Mn 3+/4+ 2NbO9 were synthesized by standard ceramic procedures; the crystallographic structure was studied from X-ray powder diffraction (XRPD) and neutron powder diffraction (NPD). Both phases exhibit a monoclinic symmetry (S.G.: P21/n); Ca3Mn 2WO9 presents a long-range ordering over the B sites, whereas Ca3Mn2NbO9 is strongly disordered. By >in-situ> NPD, the temperature evolution of the structure study presents an interesting evolution in the octahedral size (〈 Mn-OâŒ) for Ca3Mn2NbO9, driven by a charge ordering effect between Mn3+ and Mn4+ atoms, related to the anomaly observed in the transport measurements at T≈160 K. Both materials present a magnetic order below TC=30 K and 40 K for W and Nb materials, respectively. The magneto-transport measurements display non-negligible magnetoresistance properties in the paramagnetic regime.© 2013 Published by Elsevier Inc. All rights reserved., C.A.L. and M.E.S. thanks a CONICET fellowship. J.C.P. thanks CONICET (Project PIP 2008-01360), SECyT-UNSL (Project 7707 and Project 2-1612). R.D.S. acknowledges financial support of ANPCYT (Project PICT 2011-0752) and SEPCyT-UNCu (06/C389). J.C.P. and R.D.S are member of CONICET. J.A.A. acknowledges the financial support of the Spanish Ministry of Education to the project MAT2010-16404.

Polyaniline/Fe3O4 nanocomposites were prepared by a one-pot synthesis using N-(4-aminophenyl)aniline as the reagent, molecular oxygen or hydrogen peroxide as the oxidizing agents in the presence of Fe3O4 nanoparticles (NPs) in powder and ferrofluid form. Both magnetic NPs in powder and ferrofluid form showed similar catalytic behaviour. The catalytic effect is particularly evident when molecular oxygen was used as the oxidizing agent. However, concerning the morphological aspects, only the composites prepared in the presence of ferrofluid-type Fe3O4 NPs showed a preferential morphology of nanorods (between 30 and 110 nm in diameter). All the composites are superparamagnetic at room temperature but at low temperature they are in a blocked state. Inter-particle interactions significantly affect the magnetic properties of the composites. The electrical conductivity of the composites is about 10−2 S cm−1, in agreement with the values obtained for polyaniline prepared by chemical route. A mechanism of the nanorods formation is proposed.

In order to better understand the interesting magnetic behaviour found in the Rare Earth-transition metal/(spacer)/transition metal multilayers, a multilayer of Co/[Si/Gd0.36Co0.64/Si/Co]4/glass was studied by SQUID magnetic measurements and polarized neutron reflectivity. A model for the magnetic profile of the sample was proposed, which fitted well the polarized neutron reflectivity measurements at different magnetic states: ferrimagnetic/antiparallel state, under an applied field of 55 Oe, canted states (315 and 675 Oe) and saturation state (1700 Oe). It was found that even at the expected collinear states (ferrimagnet and saturation states), the magnetization was not totally collinear and there was a small component of the magnetization perpendicular to the applied field. Cajastur;FICYT;Gijon City Council;MICINN;Tekniker;University of Oviedo

Köçkar, Hakan (Balikesir Author), The influence of electrolyte pH and cathode potential on the magnetic properties of single layer Nickel films electrodeposited on polycrystalline titanium substrates was studied. The films were deposited at the electrolyte pH=3.5 +/- 0.1, 2.5 +/- 0.1 and 2.1 +/- 0.1 by varying the deposition potentials (-1.2, -1.5 and -1.8 V vs saturated calomel electrode, SCE) applied in continuous waveform. The structural analysis by X-ray diffraction revealed that the films have face-centred cubic structure. Results of the magnetic measurements obtained by vibrating sample magnetometer (VSM) indicated that the magnetic properties were affected by the electrolyte pH and the cathode potentials in terms of magnetic anisotropy. At the highest pH the films deposited at the lowest potential had in-plane magnetic anisotropy. As the electrolyte pH decreased from the high (pH=3.570.1) to low (pH=2.5 +/- 0.1), which is aided by increasing the potentials, resulted in an almost magnetic isotropy in the films. However, isotropic magnetic behaviour was observed for the film deposited at the low pH combined with the high potential (-1.8 V vs SCE). Magnetic thickness profile of the samples obtained by VSM revealed that the isotropic films have a smoother magnetic variation across the film from one edge than the anisotropic ones. This is also verified with a microscopic observation by an optical microscope and the surface of the isotropic films is observed to be smoother than that of the anisotropic ones. Furthermore, all films were found to have planar magnetic anisotropy irrespective of the pH's and the potentials.

In the present paper, we show an exhaustive microstructural characterization of thiol-capped gold nanoparticles (NPs) with two different average particle sizes. These samples are compared with the polymer-like Au(I) phase formed as a precursor during the synthesis of the thiol-capped gold NPs. The set of analysed samples shows different microstructures at the nanoscale with different proportions of Au atoms bonded either to S or to Au atoms. It has been experimentally shown that the presence of a ferromagnetic-like behaviour is associated to the formation of NPs with simultaneous presence of Au–Au and Au–S bonds. In order to explain such magnetic behaviour a possible model is proposed based on the spin–orbit coupling so that localized charges and/or spins (Au–S bonds) can trap conduction electrons (Au–Au bonds) in orbits., XAS facilities at BM29 in ESRF and the technical support from G.L. Ciatto are acknowledged. Financial support from the Spanish MEC (NAN2004-09125-C07) and “Junta de Andalucía” is also acknowledged. E. Guerrero thanks the Spanish MEC for financial support.

International audience; The prediction of core losses in a rotating electrical machine generally requires a numerical approach (finite element or integral method). However, the magnetic characteristics obtained through a standard Epstein facility and inserted in the numerical models predict losses which are quite different from those obtained experimentally. This difference can be partly explained by the presence of plastic strain close to the cutting edge of manufactured motor sheets. In the present paper, numerical functions are first established to predict the change in the magnetisation and loss curves with respect to the plastic strain level. Second, a microhardness test is used to measure the local plastic strain directly on the manufactured sheet. Finally, relations are obtained between the main magnetic properties and the position on the sheet: the resulting magnetic property profiles allow the numerical approach to be improved.