312 research outputs found
Current-perpendicular-to-plane giant magnetoresistance of a spin valve using Co2MnSi Heusler alloy electrodes
We report the current-perpendicular-to-plane giant magnetoresistance of a
spin valve with Co2MnSi (CMS) Heusler alloy ferromagnetic electrodes. A
multilayer stack of Cr/Ag/Cr/CMS/Cu/CMS/Fe25Co75/Ir28Mn72/Ru was deposited on a
MgO (001) single crystal substrate. The bottom CMS layer was epitaxially grown
on the Cr/Ag/Cr buffer layers and was ordered to the L21 structure after
annealing at 673 K. The upper CMS layer was found to grow epitaxially on the Cu
spacer layer despite the large lattice mismatch between Cu and CMS. The highest
MR ratios of 8.6% and 30.7% for CPP-GMR were recorded at room temperature and 6
K, respectively. The high spin polarization of the epitaxial CMS layers is the
most likely origin of the high MR ratio.Comment: 14 pages, 3 figures, presented at the 53rd Annual Conference on
Magnetism and Magnetic Materials, to be published in J. Appl. Phy
Large amplitude microwave emission and reduced nonlinear phase noise in Co2Fe(Ge0.5Ga0.5) Heusler alloy based pseudo spin valve nanopillars
We have studied microwave emission from a current-perpendicular-to-plane
pseudo spin valve nanopillars with Heusler alloy Co2Fe(Ga0.5Ge0.5) electrodes.
Large emission amplitude exceeding 150 nV/Hz^0.5, partly owing to the large
magnetoresistance, and narrow generation linewidth below 10 MHz are observed.
We also find that the linewidth shows significant dependence on the applied
field magnitude and its angle within the film plane. A minimum in the linewidth
is observed when the slope of the frequency versus current becomes near zero.
This agrees with theoretical prediction that takes into account non-linear
phase noise as a source for linewidth broadening
Complementary use of TEM and APT for the investigation of steels nanostructured by severe plastic deformation
The properties of bulk nanostructured materials are often controlled by
atomic scale features like segregation along defects or composition gradients.
Here we discuss about the complimentary use of TEM and APT to obtain a full
description of nanostructures. The advantages and limitations of both
techniques are highlighted on the basis of experimental data collected in
severely deformed steels with a special emphasis on carbon spatial
distribution
All-optical control of ferromagnetic thin films and nanostructures
The interplay of light and magnetism has been a topic of interest since the
original observations of Faraday and Kerr where magnetic materials affect the
light polarization. While these effects have historically been exploited to use
light as a probe of magnetic materials there is increasing research on using
polarized light to alter or manipulate magnetism. For instance deterministic
magnetic switching without any applied magnetic fields using laser pulses of
the circular polarized light has been observed for specific ferrimagnetic
materials. Here we demonstrate, for the first time, optical control of
ferromagnetic materials ranging from magnetic thin films to multilayers and
even granular films being explored for ultra-high-density magnetic recording.
Our finding shows that optical control of magnetic materials is a much more
general phenomenon than previously assumed. These results challenge the current
theoretical understanding and will have a major impact on data memory and
storage industries via the integration of optical control of ferromagnetic
bits.Comment: 21 pages, 11 figure
High strength and formable Mg-6.2Zn-0.5Zr-0.2Ca alloy sheet processed by twin roll casting
Twin roll cast and hot rolled Mg-6.2 wt%Zn alloys microalloyed with Zr, Ca, and Ag show tensile yield strength exceeding 300 MPa in the T6 (peak-aged) condition with reasonable formability in the T4 condition. The addition of Zr and Ca plays a critical role in the development of weak textured recrystallized microstructure in Mg-6.2 wt%Zn alloys so Mg-6.2Zn-0.5Zr-0.2Ca (wt%) alloy shows equivalent mechanical properties with Mg-6.2Zn-0.5Zr-0.2Ca-0.4Ag (wt%) alloy even without expensive Ag. (C) 2014 Elsevier B.V. All rights reserved.X112224Ysciescopu
- …