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Magnetoconductivity (MC), Δσ(Β), and Hall coefficient, RH(B), measurements have been performed in polycrystalline thin films of Bi(15nm), Bi(10nm)/Co(1nm)/Bi(10nm) trilayer and [Co(0.7nm)/Bi(2nm)]10 multilayer, grown by magnetron scattering. The temperature dependence of RH(B) curves reveal the existence of a second conduction channel below 250K, that can be assigned to surface states. MC measurements between ±0.4T show at 5K an interplay between weak-antilocalization (WAL) in Bi and Bi/Co/Bi films and weal-localization (WL) in [Co/Bi]10 multilayer.

A series of Co-Bi thin films with Co concentrations c=0, 0.05, 0.2, 0.26, 0.3, 0.333, 0.375, 0.545, were grown by magnetron sputtering on Si(100)/SiNX substrates. Resistivity measurements at zero field (ρxx) as a function of temperature-T exhibit an exponential variation with T in the region of 240K

A study is carried out on the effects of the metallic antiferromagnet (AF) gamma-FeMn and the AF-semiconductor NiO alloys on the polarity if anomalous Hall resistivity loops in perpendicularly biased [Pt(2 nm)/Co(0.4 nm)]15/AF (3 nm)/[Co(0.4 nm/Pt(2 nm)]15 (AF=FeMn, NiO) multilayers. The studies indicates that the hall resistivity exhibits negative polarity for AF=NiO and positive polarity for AF=FeMn.

Spin coupling in La-Ca-Mn-O multilayers is reported.

Low-field giant magnetoresistance in (111)-textured cobalt/gold multilayers that were prepared using the magnetron sputtering technique was investigated. A series of magnetron-sputtered cobalt-gold multilayers was deposited on silicon(100) substrates covered with a SiNx buffer layer. Experimental results showed that the multilayers with (111) texturing have a low-field giant magnetoresistance effect. Deposition of the multilayers on SiNx buffer layers appears to induce the development of a considerable fraction of faults in the stacking of cobalt along the growth direction.

The optical, structural and magnetotransport properties of sputtered Co/Cu multilayers were investigated in relation to the thickness of the Co layer at the second antiferromagnetic maximum using spectroscopic ellipsometry and X-ray reflectivity (XRR). The Co/Cu interlayer and silicon nitride buffer layer root-mean-square roughness and the mean density were then derived from the XRR spectra. The findings showed that the systematic variation of the real and imaginary components of the dielectric function depended on the thickness of the Co layer.

A significant variation in shape and magnitude of giant-magnetoresistance (GMR), and in magnetic (M-H) loops, has been seen for three different classes of (Co/1.1 nm/Cu/2.1 nm)30 multilayers. Transmission electron microscopy revealed two well-separated grain size distributions below and above 12 nm. It was possible to obtain some important results connecting microstructure with optimum sensing conditions of GMR curves in sputtered Co/Cu multilayers. These include the fact that the growth of structures with average size less than 10 nm seems to increase the fraction of ferromagnetic areas.

The physics underlying the magnetoresistance-related behavior of ultrathin, as-deposited Ni18Fe19/Ag discontinuous multilayers were characterized as a function of Ag and NiFe layer thickness. Based on results obtained through x-ray diffraction, magnetotransport, and hysteresis loop measurements, it was found that the Ag layer thickness affects the ferromagnetic coupling and oscillations of coercivity Hc and residual magnetization Mr when the temperature is five Kelvin.

A study was conducted to analyze a series of multilayers support bilayer thicknesses between 2 and 23 nm. The multilayers were made using pulsed laser deposition of bulk stoichiometric targets on single crystal substrates. Experimental results indicated the presence of an exchange biasing mechanism at low temperatures. Findings also showed a blocking temperature around 70 K that is independent of the bilayer thickness.

The effect of the metallic antiferromagnet (AF) γ-FeMn and the AF-semiconductor NiO alloys on the polarity of anomalous Hall resistivity loops is examined in perpendicularly biased [Pt(2 nm)/Co(0.4 nm)]15/AF(3 nm)/[Co(0.4 nm)/Pt(2 nm)]15 (AF=NiO, FeMn) multilayers. The Hall resistivity exhibits negative polarity for AF=NiO and positive polarity for AF=FeMn. These differences are explained by the reduced spin-diffusion-length effects and the specular reflection of electrons at FeMn and NiO interfaces, respectively. In addition, it is shown that a sandwiched AF thin layer stabilizes the exchange-bias effect via interlayer coupling between top [Co(0.4 nm)/Pt(2 nm)]15 and bottom [Pt(2 nm)/Co(0.4 nm)]15 structures in multilayers with strong perpendicular magnetic anisotropy. [ABSTRACT FROM AUTHOR]

(111) oriented [Co(1 nm)/Au(2.5 nm)][SUB30] multilayers exhibit a strong thermal variation of the magnetoresistive (MR) signal between 5 and 280 K, that consists of field-direction dependent giant (GMR) and anisotropic magnetoresistance (AMR) contributions. Both, isothermal magnetization and the MR loops reveal the appearance of a canted magnetic state that accompanies the enhancement of the AMR contribution at lower temperatures. In addition, the experimental results reveal that the GMR and AMR contributions not only depend on the relative direction between the magnetic field and the current but also depend strongly on the relative direction of the field and the tilting angle of the mean easy-magnetization axis. The large differences observed in the magnetization and the MR curves of the as-made and the annealed films reveal the important role played by the field dependence of the magnetic domain correlations in the spin conductance of face-centered-cubic-Co/Au multilayers. [ABSTRACT FROM AUTHOR]

Strained epitaxial bilayers and multilayers consisting of La[sub 1-χ]Ca[sub χ]MnO[sub 3] ferromagnetic (FM) layers (χ = 0.33, 0.4) and La[sub 0.33]Ca[sub 0.67]MnO[sub 3] antiferromagnetic (AF) layers were grown on (001)LaAlO[sub 3] to study the evolution of exchange coupling interactions. The epitaxy was revealed by conventional and high resolution electron microscopy. An out-of-plane lattice expansion is observed mainly on the FM layers that induces a spontaneous magnetization component normal to the film plane. Field-cooling experiments with the applied field parallel and perpendicular to the film plane exhibit loop-shifts (exchange biasing) and enhanced coercivities that depend on the spin projections at the AF/FM interfaces. [ABSTRACT FROM AUTHOR]

Investigates the micromagnetic properties that result in low-field giant-magnetoresistance (GMR) by measuring the temperature dependence of isothermal magnetic and GMR loops in three classes of multilayers. Structural characterization; Magnetic measurements; GMR results.