Browsing Exact and Earth Sciences by Title

Now showing items 2927-2946 of 5964

    • 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) [Journal article]
      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) [Journal article]
      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) [Journal article]
      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) [Journal article]
      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) [Journal article]
      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) [Journal article]
      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) [Journal article]
      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) [Journal article]
      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) [Journal article]
      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) [Journal article]
      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) [Journal article]
      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) [Journal article]
      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) [Journal article]
      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) [Journal article]
      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) [Journal article]
      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) [Journal article]
      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) [Journal article]
      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) [Journal article]
      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) [Journal article]
      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 ...

    • Magnetostriction in ar/sup +/ implanted and annealed co/pd multilayers 

      Viegas, Alexandre da Cas; Schelp, Luiz Fernando; Schmidt, Joao Edgar (1995) [Journal article]
      Magnetostriction curves with (111) textured polycrystalline Co/Pd multilayers, as deposited or submitted to ArS ion implantation or thermal annealing, are presented and discussed. Both treatments, while promoting intermixing ...