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Your search keyword '"Manuel Varela"' showing total 3 results
Start Over Author "Manuel Varela" Journal nanotechnology
3 results on '"Manuel Varela"'

1. Particle growth mechanisms in Ag–ZrO2and Au–ZrO2granular films obtained by pulsed laser deposition

Author

Manuel Varela, Amílcar Labarta, Montserrat García del Muro, Zorica Konstantinović, and Xavier Batlle

Subjects
Condensed Matter - Materials Science, Materials science, Mechanical Engineering, Nucleation, Analytical chemistry, Materials Science (cond-mat.mtrl-sci), FOS: Physical sciences, Bioengineering, Percolation threshold, Disordered Systems and Neural Networks (cond-mat.dis-nn), General Chemistry, Condensed Matter - Disordered Systems and Neural Networks, Amorphous solid, Pulsed laser deposition, Mechanics of Materials, Particle, General Materials Science, Particle size, Electrical and Electronic Engineering, Thin film, High-resolution transmission electron microscopy
Abstract

Thin films consisting of Ag and Au nanoparticles embedded in amorphous ZrO2 matrix were grown by pulsed laser deposition in a wide range of metal volume concentrations in the dielectric regime (0.08, Comment: 6 figures

Published
2006
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2. Controlling exchange bias in Co-CoOx nanoparticles by oxygen content

Author

Xavier Batlle, Amílcar Labarta, Òscar Iglesias, M. Kovylina, Manuel Varela, Montserrat García del Muro, and Zorica Konstantinović

Subjects
Condensed Matter - Materials Science, Materials science, Mechanical Engineering, Analytical chemistry, Materials Science (cond-mat.mtrl-sci), FOS: Physical sciences, Bioengineering, General Chemistry, Amorphous solid, chemistry.chemical_compound, Hysteresis, Exchange bias, Ferromagnetism, chemistry, Mechanics of Materials, Phase (matter), Antiferromagnetism, General Materials Science, Condensed Matter::Strongly Correlated Electrons, Electrical and Electronic Engineering, Thin film, AFm phase
Abstract

We report on the occurrence of exchange bias on laser-ablated granular thin films composed of Co nanoparticles embedded in amorphous zirconia matrix. The deposition method allows controlling the degree of oxidation of the Co particles by tuning the oxygen pressure at the vacuum chamber (from 2x10^{-5} to 10^{-1} mbar). The nature of the nanoparticles embedded in the nonmagnetic matrix is monitored from metallic, ferromagnetic (FM) Co to antiferromagnetic (AFM) CoOx, with a FM/AFM intermediate regime for which the percentage of the AFM phase can be increased at the expense of the FM phase, leading to the occurrence of exchange bias in particles of about 2 nm in size. For oxygen pressure of about 10-3 mbar the ratio between the FM and AFM phases is optimum with an exchange bias field about 900 Oe at 1.8 K. The mutual exchange coupling between the AFM and FM is also at the origin of the induced exchange anisotropy on the FM leading to high irreversible hysteresis loops, and the blocking of the AFM clusters due to proximity to the FM phase., 12 pages, 8 figures. To be published in Nanotechnology

Published
2009

3. Controlling exchange bias in Co-CoOx nanoparticles by oxygen content.

Author

Miroslavna Kovylina, Montserrat Garcia, del Muro, Zorica Konstantinovic, Manuel Varela, Oscar Iglesias, Amilcar Labarta, and Xavier Batlle

Subjects
METAL clusters, MAGNETIZATION, LASER ablation, METALLIC films, OXIDATION, COBALT, OXYGEN, ZIRCONIUM oxide
Abstract

We report on the occurrence of exchange bias on laser-ablated granular thin films composed of Co nanoparticles embedded in an amorphous zirconia matrix. The deposition method allows one to control the degree of oxidation of the Co particles by tuning the oxygen pressure at the vacuum chamber (from 2 x 10[?]5 to 10[?]1 mbar). The nature of the nanoparticles embedded in the nonmagnetic matrix is monitored from metallic, ferromagnetic (FM) Co to antiferromagnetic (AFM) CoOx, with a FM/AFM intermediate regime for which the percentage of the AFM phase can be increased at the expense of the FM phase, leading to the occurrence of exchange bias in particles of about 2 nm in size. For an oxygen pressure of about 10[?]3 mbar the ratio between the FM and AFM phases is optimum with an exchange bias field of about 900 Oe at 1.8 K. The mutual exchange coupling between the AFM and FM is also at the origin of the induced exchange anisotropy on the FM leading to high irreversible hysteresis loops, and the blocking of the AFM clusters due to proximity to the FM phase. [ABSTRACT FROM AUTHOR]

Published
2009
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