1,673 research outputs found
Prediction of novel interface-driven spintronic effects
The recently-proposed coupling between the angular momentum density and
magnetic moment [A. Raeliarijaona et al, Phys. Rev. Lett. 110, 137205 (2013)]
is shown here to result in the prediction of (i) novel spin currents generated
by an electrical current and (ii) new electrical currents induced by a spin
current in systems possessing specific interfaces between two different
materials. Some of these spin (electrical) currents can be reversed near the
interface by reversing the applied electrical (spin) current. Similarities and
differences between these novel spintronic effects and the well-known spin Hall
and inverse spin Hall effects are also discussed.Comment: Accepted in J. Phys.::Condens. Matte
Comparative Measurements of Inverse Spin Hall and Magnetoresistance in YIG|Pt and YIG|Ta
We report on a comparative study of spin Hall related effects and
magnetoresistance in YIG|Pt and YIG|Ta bilayers. These combined measurements
allow to estimate the characteristic transport parameters of both Pt and Ta
layers juxtaposed to YIG: the spin mixing conductance
at the YIGnormal metal interface, the spin Hall angle , and the
spin diffusion length in the normal metal. The inverse spin Hall
voltages generated in Pt and Ta by the pure spin current pumped from YIG
excited at resonance confirm the opposite signs of spin Hall angles in these
two materials. Moreover, from the dependence of the inverse spin Hall voltage
on the Ta thickness, we extract the spin diffusion length in Ta, found to be
nm. Both the YIG|Pt and YIG|Ta systems
display a similar variation of resistance upon magnetic field orientation,
which can be explained in the recently developed framework of spin Hall
magnetoresistance.Comment: 8 pages, 5 figures, 1 tabl
Detection of the microwave spin pumping using the inverse spin Hall effect
We report electrical detection of the dynamical part of the spin pumping
current emitted during ferromagnetic resonance (FMR) using the inverse Spin
Hall Effect (ISHE). The experiment is performed on a YIGPt bilayer. The
choice of YIG, a magnetic insulator, ensures that no charge current flows
between the two layers and only pure spin current produced by the magnetization
dynamics are transferred into the adjacent strong spin-orbit Pt layer via spin
pumping. To avoid measuring the parasitic eddy currents induced at the
frequency of the microwave source, a resonance at half the frequency is induced
using parametric excitation in the parallel geometry. Triggering this nonlinear
effect allows to directly detect on a spectrum analyzer the microwave component
of the ISHE voltage. Signals as large as 30 V are measured for precession
angles of a couple of degrees. This direct detection provides a novel efficient
means to study magnetization dynamics on a very wide frequency range with great
sensitivity
Fabrication and structural characterization of highly ordered sub-100-nm planar magnetic nanodot arrays over 1 cm2 coverage area
Porous alumina masks are fabricated by anodization of aluminum films grown on both semiconducting and insulating substrates. For these self-assembled alumina masks, pore diameters and periodicities within the ranges of 10–130 and 20–200nm, respectively, can be controlled by varying anodization conditions. 20nm periodicities correspond to pore densities in excess of 1012 per square inch, close to the holy grail of media with 1Tbit∕in.2 density. With these alumina masks, ordered sub-100-nm planar ferromagnetic nanodot arrays covering over 1cm2 were fabricated by electron beam evaporation and subsequent mask lift-off. Moreover, exchange-biased bilayer nanodots were fabricated using argon-ion milling. The average dot diameter and periodicity are tuned between 25 and 130nm and between 45 and 200nm, respectively. Quantitative analyses of scanning electron microscopy (SEM) images of pore and dot arrays show a high degree of hexagonal ordering and narrow size distributions. The dot periodicity obtained from grazi..
Terahertz wave generation via optical rectification from multiferroic BiFeO3
We detected broadband coherent terahertz (THz) emission from multiferroic
BiFeO3 after illuminating a high-quality bulk single ferroelectric domain
crystal with a ~100 fs optical pulse. The dependence of the emitted THz
waveform on the energy and polarization of the optical pulse is consistent with
the optical rectification mechanism of THz emission. The THz emission provides
a sensitive probe of the electric polarization state of BiFeO3, enabling
applications in ferroelectric memories and ferroelectric domain imaging. We
also report room-temperature THz optical constants of BiFeO3.Comment: accepted for publication in Applied Physics Letter
Bismuth-based perovskites as multiferroics
This review devoted to multiferroic properties of Bismuth-based perovskites
falls into two parts. The first part focuses on BiFeO3 and summarizes the
recent progress made in the studies of its pressure-temperature phase diagram
and magnetoelectric coupling phenomena. The second part discusses in a more
general way the issue of polar - and multiferroic - phases in BiBO3 perovskites
and the competition between ferroelectricity and other structural
instabilities, from an inventory of recently synthetized compounds.Comment: 22 pages, 7 figures, to be published in Comptes Rendus Physiqu
Ultrafast behavior of induced and intrinsic magnetic moments in CoFeB/Pt bilayers probed by element-specific measurements in the extreme ultraviolet spectral range
The ultrafast and element-specific response of magnetic systems containing ferromagnetic 3d transition metals and 4d/5d heavy metals is of interest both from a fundamental as well as an applied research perspective. However, to date no consensus about the main microscopic processes describing the interplay between intrinsic 3d and induced 4d/5d magnetic moments upon femtosecond laser excitation exist. In this work we study the ultrafast response of CoFeB/Pt bilayers by probing element-specific, core-to-valence-band transitions in the extreme ultraviolet spectral range using high harmonic radiation. We show that the combination of magnetic scattering simulations and analysis of the energy- and time-dependent magnetic asymmetries allows us to accurately disentangle the element-specific response in spite of overlapping Co and Fe M2,3 as well as Pt O2,3 and N7 resonances. We find a considerably smaller demagnetization time constant as well as much larger demagnetization amplitudes of the induced moment of Pt compared to the intrinsic moment of CoFeB. Our results are in agreement with enhanced spin-flip probabilities due to the high spin-orbit coupling localized at the heavy metal Pt, as well as with the recently formulated hypothesis that a laser-generated, incoherent magnon population within the ferromagnetic film leads to an overproportional reduction of the induced magnetic moment of Pt
Docetaxel- and 5-FU-concurrent radiotherapy in patients presenting unresectable locally advanced pancreatic cancer: a FNCLCC-ACCORD/0201 randomized phase II trial's pre-planned analysis and case report of a 5.5-year disease-free survival
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