Search Results - (Author, Cooperation:M. Respaud)
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1Latest Papers from Table of Contents or Articles in PressP. Huang ; C. Lethien ; S. Pinaud ; K. Brousse ; R. Laloo ; V. Turq ; M. Respaud ; A. Demortiere ; B. Daffos ; P. L. Taberna ; B. Chaudret ; Y. Gogotsi ; P. Simon
American Association for the Advancement of Science (AAAS)
Published 2016Staff ViewPublication Date: 2016-02-26Publisher: American Association for the Advancement of Science (AAAS)Print ISSN: 0036-8075Electronic ISSN: 1095-9203Topics: BiologyChemistry and PharmacologyComputer ScienceMedicineNatural Sciences in GeneralPhysicsPublished by: -
2Articles: DFG German National LicensesGarcía-Muñoz, J. L. ; Respaud, M. ; Frontera, C.
[S.l.] : American Institute of Physics (AIP)
Published 1999Staff ViewISSN: 1089-7550Source: AIP Digital ArchiveTopics: PhysicsNotes: Well characterized Ln1−xCaxMnO3 manganites (Ln=La, Pr, Nd, Sm) with x=1/2 and x=1/3 have been investigated by magnetization measurements in pulsed magnetic fields up to 50 T. Using such high fields all the CO phase boundaries were identified in the temperature range 4–300 K. The transition fields at 4.2 K have been determined in a series of polycrystalline samples with x=1/2 and different effective bandwidths. They vary from Hc=8 T for La to (approximate)30 T for Sm. In this article we have focused on selected H–T phase diagrams. In particular, the results on Pr1/2Ca1/2MnO3, with the ideal 1:1 electron/hole ratio, are compared with Pr2/3Ca1/3MnO3 where the carrier concentration has been significantly reduced. The observed anomalies in the Hc(T) curves are discussed in the light on neutron diffraction data. © 1999 American Institute of Physics.Type of Medium: Electronic ResourceURL: -
3Articles: DFG German National LicensesStaff View
ISSN: 1089-7550Source: AIP Digital ArchiveTopics: PhysicsNotes: Magnetization measurements were performed and analyzed on two systems of noninteracting superparamagnetic cobalt nanoparticles displaying narrow size distributions. The experiments were carried out above the blocking temperature, i.e., in the superparamagnetic regime. Several deviations from classical Langevin behavior were pointed out, in particular, at high field and near the blocking temperature. These deviations were interpreted in terms of anisotropy effects on the magnetization process and analyzed using theoretical expressions including uniaxial anisotropy energy. The effect of the anisotropy on the theoretical magnetization curves plotted versus applied field divided by the temperature are characterized by: (i) superposition at low fields, (ii) deviations in the approach to saturation area, and (iii) decrease of the magnetization when lowering the temperature. These three characteristics are present in our experimental curves. It allows us to determine the magnetic moment of the particle in the low-field region, and then the effective anisotropy from the approach to the saturation area for each sample, validating therefore, our theoretical expressions. A more detailed analysis of the experimental magnetization curves showed that the magnetization process proceeds in two steps: orientation of the magnetic moment of the particle, and orientation of the canted spins in the particle along the applied field. Finally, the values of the effective anisotropy are compared with those determined by other techniques. © 1999 American Institute of Physics.Type of Medium: Electronic ResourceURL: