Navegação Ciências Exatas e da Terra por Título

Resultados 2931-2950 de 5972

    • Magnetic interactions in the ludwigite Ni/sub 2/FeO/sub 2/BO/sub 3/ 

      Fernandes, Joao Carlos; Guimaraes, Renato Bastos; Continentino, Mucio Amado; Borges, Hortencio A.; Sulpice, A.; Tholence, Jean-Louis; Siqueira, Jesumar Lopes; Zawislak, Luci Irene; Cunha, Joao Batista Marimon da; Santos, Carlos Alberto dos (1998) [Artigo de periódico]
      We present an investigation of the magnetic properties of the ludwigite Ni2FeO2BO3. This material is an oxyborate that presents in its crystalline structure subunits in the form of walls where the transition metal ions are ...

    • Magnetic materials enriched with strontium : a study of the use as catalysts in the transesterification reaction of babassu oil 

      Abreu, Wiury Chaves de; Moraes, Ana Flávia; Reis, Roberta Yonara Nascimento; Pinto, Bernardo Ferreira; Moura, Carla Verônica Rodarte de; Nicolodi, Sabrina; Moura, Edmilson Miranda de (2019) [Artigo de periódico]
      This work described a new magnetic material enriched with strontium as catalyst to produce babassu biodiesel. The use of magnetic materials has attracted attention due to easy and fast separation from reaction medium. ...

    • Magnetic ordering in YGd alloys 

      Pureur Neto, Paulo; Fert, Albert R.; Wendler, R.; Baberschke, Klaus (1985) [Artigo de periódico]
      We present magnetization and resistivity measurements on single crystals of yttrium doped with small concentrations of gadolinium (c = 1, 2, and 3 at. %). The low-field susceptibility exhibits a spin-glass-like sharp cusp ...

    • Magnetic properties of Nd/Fe double layers grown on Si(111) by electron beam evaporation 

      Fermin, Jose R.; Azevedo, Antonio; Rezende, Sergio Machado; Pereira, Luis Gustavo; Teixeira, Sergio Ribeiro (1998) [Artigo de periódico]
      In-plane ferromagnetic resonance (FMR) has been used to study the room-temperature magnetic and crystalline properties of Nd/Fe bilayers. Several samples were grown by electron beam evaporation onto Si(111) substrates, for ...

    • Magnetic susceptibility and specific heat of the anderson lattice : perturbative expansion around the atomic limit 

      Brunnet, Leonardo Gregory; Gusmao, Miguel Angelo Cavalheiro; Iglesias, Jose Roberto (1992) [Artigo de periódico]
      The Green's functions relevant to the periodic Anderson Hamiltonian are calculated via perturbation theory around the atomic limit. The approximation reproduces exact results in three different limits: zero bandwidth, zero ...

    • Magnetic susceptibility of fe/cu multilayers : ferromagnetic, antiferromagnetic, and spin-glass phases 

      Oliveira, A.J.A. de; Ortiz, Wilson Aires; Mosca Junior, Dante Homero; Mattoso Filho, Ney Pereira; Schreiner, Wido Herwig; Teixeira, Sergio Ribeiro (1998) [Artigo de periódico]
      In this work we present low-field magnetic measurements on multilayers of Fe 1.5 nm and Cu 1.5 nm layers, repeated 10 times, grown on Si~111! and Fe 5 nm/CaF2 40 nm/Si(111), substrates. Magnetic characteristics of a ...

    • Magnetic white dwarf stars in the Sloan Digital Sky Survey 

      Kepler, Souza Oliveira; Pelisoli, Ingrid Domingos; Jordan, Stefan; Kleinman, Scot James; Koester, Detlev; Kulebi, Baybars; Antonio, Viviane Peçanha; Castanheira, Bárbara Garcia; Nitta, Atsuko; Costa, Jose Eduardo da Silveira; Winget, Donald Earl; Kanaan Neto, Antonio Nemer; Fraga, Luciano (2013) [Artigo de periódico]
      To obtain better statistics on the occurrence of magnetism among white dwarfs, we searched the spectra of the hydrogen atmosphere white dwarf stars (DAs) in the Data Release 7 of the Sloan Digital Sky Survey (SDSS) for ...

    • Magnetism and quantum phase transitions in spin-1/2 attractive fermions with polarization 

      He, Jingsong; Foerster, Angela; Guan, Xi-Wen; Batchelor, Murray T. (2009) [Artigo de periódico]
      An extensive investigation is given for magnetic properties and phase transitions in one-dimensional (1D) Bethe ansatz integrable spin-1/2 attractive fermions with polarization by means of the dressed energy formalism. An ...

    • Magnetism in dilute magnetic oxide thin films based on SnO/sub 2/ 

      Fitzgerald, C.B.; Venkatesan, M.; Dorneles, Lucio Strazzabosco; Gunning, R.; Stamenov, Plamen; Coey, John Michael Douglas; Stampe, P.A.; Kennedy, R.J.; Moreira, Eduardo Ceretta; Sias, Uilson Schwantz (2006) [Artigo de periódico]
      Thin films of SnO2 prepared by pulsed-laser deposition on R-cut sapphire substrates exhibit ferromagnetic properties at room temperature when they are doped with Cr, Mn, Fe, Co, or Ni, but not with other 3d cations. ...

    • Magnetism, magnetoresistance, and Shubnikov-de Haas oscillations in Na-implanted highly oriented pyrolitic graphite 

      Pires, Rafael Fernando; Pureur Neto, Paulo; Behar, Moni; Pimentel Junior, Jorge Luiz; Schaf, Jacob; Kopelevich, Y. (2012) [Artigo de periódico]
      We report on magnetization, magnetoresistance, and Shubnikov-de Haas oscillations experiments in Na-implanted samples of highly oriented pyrolitic graphite (HOPG). Different ion fluences were applied so that samples with ...

    • Magnetization dynamics as derived from magneto impedance measurements 

      Carara, Marcos Andre; Baibich, Mario Norberto; Sommer, Rubem Luis (2000) [Artigo de periódico]
      In this work, the magnetization dynamics of soft magnetic materials is studied with the aid of transverse differential permeability μ(Iac , f ,Hdc) spectra. Contributions to the magnetization processes from domain wall ...

    • Magnetization dynamics in nanostructures with weak/strong anisotropy 

      Andrade, Antonio Marcos Helgueira de; Corrêa, Marcio Assolin; Viegas, Alexandre da Cas; Bohn, Felipe; Sommer, Rubem Luis (2014) [Artigo de periódico]
      We investigate the high-frequency response of magnetization dynamics through magnetoimpedance (MI) effect in Permalloy-based multilayered thin films produced with two different non-magnetic metallic spacers: Cu and Ag. Due ...

    • Magnetization process and magnetoimpedance in (110)[001]FeSi/Sub 3% 

      Carara, Marcos Andre; Gundel, Andre; Baibich, Mario Norberto; Sommer, Rubem Luis (1998) [Artigo de periódico]
      The present article investigates the relation between magnetoimpedance (MI) and the evolution of the magnetic domain structure along the magnetization curves of commercial FeSi3% sheets cut at different angles with respect ...

    • Magnetoconductivity of a disordered electron system with n orbitals persite 

      Magalhaes, Sergio Garcia; Theumann, Alba Graciela Rivas de (1994) [Artigo de periódico]
      In the absence of a magnetic field, two formally equivalent expressions for the conductivity contribute different sets of Feynman diagrams, due to cancellations. We use this result to calculate the magnetoconductivity of ...

    • Magnetoelectric effect and phase transitions in CuO in external magnetic fields 

      Wang, Zhaosheng; Qureshi, Navid; Yasin, Shadi; Mukhin, Alexander; Ressouche, Eric; Zherlitsyn, Sergei; Skourski, Yurii; Geshev, Julian Penkov; Ivanov, Vsevolod; Gospodinov, Marin; Skumryev, Vassil (2016) [Artigo de periódico]
      Apart from being so far the only known binary multiferroic compound, CuO has a much higher transition temperature into the multiferroic state, 230 K, than any other known material in which the electric polarization is ...

    • Magnetometria in-situ para caracterização de materiais eletrodepositados 

      Franco, Vinícius Cappellano de; Schmidt, Joao Edgar (2019) [Artigo de periódico]
      We have recently made studies of electrodeposits of Co onto graphene attached to different substrates, successfully performed via in-situ magnetization measurements. The magnetic analysis of deposits as a function of time ...

    • Magnetoresistance in rf-sputtered(nife/cu/co/cu) spin-valve multilayers 

      Lottis, Daniel Kurt; Fert, Albert R.; Morel, Robert; Pereira, Luis Gustavo; Jacquet, J.C.; Galtier, P.; Coutellier, J.M.; Valet, Tierry (1993) [Artigo de periódico]
      A study of the vtiation of the magnetoresistancein (Ni80Fe20/Cu/Co/Cu) multilayers with the thicknesses tNiFe, tcO, and &;cu of each type of component layer has been performed. The magnetoresistance (MR), which at 4 .2 K ...

    • Magnetoresistance of doped silicon 

      Silva, Antonio Ferreira da; Levine, Alexandre; Momtaz, Zahra Sadre; Boudinov, Henri Ivanov; Sernelius, Bo E. (2015) [Artigo de periódico]
      We have performed longitudinal magnetoresistance measurements on heavily n-doped silicon for donor concentrations exceeding the critical value for the metal-nonmetal transition. The results are compared to those from a ...

    • Magnetoresistance of pd-fe and pd-ni-fe alloys 

      Hsu, Y.; Schmidt, Joao Edgar; Gupta, M.; Jen, S.; Berger, Luc (1983) [Artigo de periódico]
      The electrical resistivity ofPd-Fe alloys has been measured in magnetic fields parallel and perpendicular to the current, for a wide range of alloy compositions. The influence of atomic ordering on the magnetoresistance ...

    • Magnetosonic waves in a quantum plasma with arbitrary electron degeneracy 

      Haas, Fernando; Mahmood, Shahzad (2018) [Artigo de periódico]
      Using a two-species quantum hydrodynamic model, we derive the quantum counterpart of magnetosonic waves, in a plasma with arbitrary degree of degeneracy and taking into account quantum diffraction effects due to the ...