39 research outputs found
Hyperfine Fields in an Ag/Fe Multilayer Film Investigated with 8Li beta-Detected Nuclear Magnetic Resonance
Low energy -detected nuclear magnetic resonance (-NMR) was used
to investigate the spatial dependence of the hyperfine magnetic fields induced
by Fe in the nonmagnetic Ag of an Au(40 \AA)/Ag(200 \AA)/Fe(140 \AA) (001)
magnetic multilayer (MML) grown on GaAs. The resonance lineshape in the Ag
layer shows dramatic broadening compared to intrinsic Ag. This broadening is
attributed to large induced magnetic fields in this layer by the magnetic Fe
layer. We find that the induced hyperfine field in the Ag follows a power law
decay away from the Ag/Fe interface with power , and a field
extrapolated to T at the interface.Comment: 5 pages, 4 figure. To be published in Phys. Rev.
Femtosecond control of electric currents at the interfaces of metallic ferromagnetic heterostructures
The idea to utilize not only the charge but also the spin of electrons in the
operation of electronic devices has led to the development of spintronics,
causing a revolution in how information is stored and processed. A novel
advancement would be to develop ultrafast spintronics using femtosecond laser
pulses. Employing terahertz (10 Hz) emission spectroscopy, we
demonstrate optical generation of spin-polarized electric currents at the
interfaces of metallic ferromagnetic heterostructures at the femtosecond
timescale. The direction of the photocurrent is controlled by the helicity of
the circularly polarized light. These results open up new opportunities for
realizing spintronics in the unprecedented terahertz regime and provide new
insights in all-optical control of magnetism.Comment: 3 figures and 2 tables in the main tex
Spin Seebeck insulator
Thermoelectric generation is an essential function of future energy-saving
technologies. However, this generation has been an exclusive feature of
electric conductors, a situation which inflicts a heavy toll on its
application; a conduction electron often becomes a nuisance in thermal design
of devices. Here we report electric-voltage generation from heat flowing in an
insulator. We reveal that, despite the absence of conduction electrons, a
magnetic insulator LaY2Fe5O12 converts a heat flow into spin voltage. Attached
Pt films transform this spin voltage into electric voltage by the inverse spin
Hall effect. The experimental results require us to introduce thermally
activated interface spin exchange between LaY2Fe5O12 and Pt. Our findings
extend the range of potential materials for thermoelectric applications and
provide a crucial piece of information for understanding the physics of the
spin Seebeck effect.Comment: 19 pages, 5 figures (including supplementary information
Magnetic properties of NiMnSb(001) films grown on InGaAs/InP(001)
NiMnSb half Heusler alloy films were prepared by molecular beam epitaxy (MBE) on InP(001). The dc and rf magnetic properties were investigated
by ferromagnetic resonance (FMR). The effective uniaxial anisotropy
fields increased with increasing film thickness and reached nonzero
asymptotic values. FMR linewidths rapidly increased with the film
thickness due to the presence of two magnon scattering. Bulklike
uniaxial anisotropies and two magnon scattering were caused by a
self-assembled network of lattice defects. Gilbert damping parameter
and spectroscopic g factor were found to be 3.1x10(7) and 2.03,
respectively, indicating a weak role of spin orbit interaction. (C)
2004 American Institute of Physics
Structural and magnetic properties of NiMnSb/InGaAs/InP(001)
The structural and magnetic properties of NiMnSb films, 5-120 nm thick, grown on InGaAs/InP(001) substrates by molecular-beam epitaxy, were
studied by x-ray diffraction, transmission electron microscopy (TEM),
and ferromagnetic resonance (FMR) techniques. X-ray diffraction and TEM
studies show that the NiMnSb films had the expected half-Heusler
structure, and films up to 120 nm were pseudomorphically strained at
the interface, greater than the critical thickness for this system,
about 70 nm (0.6% mismatch to InP). No interfacial misfit dislocations
were detected up to 85 nm, however, relaxation in the surface regions
of films thicker than 40 nm was evident in x-ray reciprocal space maps.
TEM investigations show that bulk, planar defects are present beginning
in the thinnest film (10 nm). Their density remains constant but they
gradually increase in size with increasing film thickness. By 40 nm
these defects have overlapped to form a quasicontinuous network aligned
closely with < 100 > in-plane directions. The associated strain fields
and or compositional ordering from these defects introduced a reduction
in crystal symmetry that influenced the magnetic properties. The
in-plane and perpendicular FMR anisotropies are not well described by
bulk and interface contributions. In thick films, the in-plane uniaxial
and fourfold anisotropies increased with increasing film thickness. The
lattice defects resulted in a large extrinsic magnetic damping caused
by two-magnon scattering, an increase in the coersive field with
increasing film thickness, and a lower magnetic moment (3.6 Bohr
magnetons) compared to the expected value for the bulk crystals (4 Bohr
magnetons). (C) 2005 American Institute of Physics
Laser induced spin precession in highly anisotropic granular L1(0) FePt
Contains fulltext :
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Doubly-Bound Relationship Between Publisher and Retailer: The Curious Mix of Wholesale and Agency Models
Magnetization dynamics of the ferrimagnet CoGd near the compensation of magnetization and angular momentum
Magnetization dynamics in alloys of ferrimagnetic CoGd have been studied in the vicinity of the magnetization and angular momentum
compensation point as a function of alloy composition and temperature.
In agreement with standard mean-field treatments of the dynamics of the
total magnetization we observe an increase of the precessional
frequency and the effective damping parameter near the angular momentum
compensation point. We demonstrate the consistency of the magnetization
dynamics extracted from frequency domain methods such as ferromagnetic
resonance and time resolved laser pump-probe measurements
Understanding RRAM endurance, retention and window margin trade-off using experimental results and simulations
International audienceIn this paper we clarify for the first time the correlation between endurance, window margin and retention of Resistive RAM. To this aim, various classes of RRAM (OXRAM and CBRAM) are investigated, showing high window margin up to 10 10 cycles or high 300°C retention. From first principle calculations, we analyze the conducting filament composition for the various RRAM technologies, and extract the key filament features. We then propose an analytical model to calculate the dependence between endurance, window margin and retention, linking material parameters to memory characteristics