3,433 research outputs found
Single spin-torque vortex oscillator using combined bottom-up approach and e-beam lithography
A combined bottom-up assembly of electrodeposited nanowires and electron beam
lithography technique has been developed to investigate the spin transfer
torque and microwave emission on specially designed nanowires containing a
single Co/Cu/Co pseudo spin valve. Microwave signals have been obtained even at
zero magnetic field. Interestingly, high frequency vs. magnetic field
tunability was demonstrated, in the range 0.4 - 2 MHz/Oe, depending on the
orientation of the applied magnetic field relative to the magnetic layers of
the pseudo spin valve. The frequency values and the emitted signal frequency as
a function of the external magnetic field are in good quantitative agreement
with the analytical vortex model as well as with micromagnetic simulations.Comment: 9 pages, 4 figure
Optimizing magneto-dipolar interactions for synchronizing vortex based spin-torque nano-oscillators
We report on a theoretical study about the magneto-dipolar coupling and
synchronization between two vortex-based spin-torque nano-oscillators. In this
work we study the dependence of the coupling efficiency on the relative
magnetization parameters of the vortices in the system. For that purpose, we
combine micromagnetic simulations, Thiele equation approach, and analytical
macro-dipole approximation model to identify the optimized configuration for
achieving phase-locking between neighboring oscillators. Notably, we compare
vortices configurations with parallel (P) polarities and with opposite (AP)
polarities. We demonstrate that the AP core configuration exhibits a coupling
strength about three times larger than in the P core configuration.Comment: 8 pages, 11 figure
Magnetic Behavior of Co/Pt and TbCo Nanocaps Assembly for Bit Pattern Media
Large area patterning of self-assembled alumina nanobumps, with hexagonally close-packed order, has
been used to create ordered array of bit pattern magnetic media. We have studied the magnetic properties
of perpendicular magnetic TbCo alloy and Co/Pt multilayers deposited on self assembled alumina
nanobumps. Measurement of reversal field as a function of field intensity, as well as magnetic force
microscopy images confirm the weakness of exchange coupling between bits in the case of Co/Pt multilayer
while stronger coupling is observed in the case of TbCo alloys.
When you are citing the document, use the following link http://essuir.sumdu.edu.ua/handle/123456789/3535
Microwave neural processing and broadcasting with spintronic nano-oscillators
Can we build small neuromorphic chips capable of training deep networks with
billions of parameters? This challenge requires hardware neurons and synapses
with nanometric dimensions, which can be individually tuned, and densely
connected. While nanosynaptic devices have been pursued actively in recent
years, much less has been done on nanoscale artificial neurons. In this paper,
we show that spintronic nano-oscillators are promising to implement analog
hardware neurons that can be densely interconnected through electromagnetic
signals. We show how spintronic oscillators maps the requirements of artificial
neurons. We then show experimentally how an ensemble of four coupled
oscillators can learn to classify all twelve American vowels, realizing the
most complicated tasks performed by nanoscale neurons
Yacon syrup: food applications and impact on satiety in healthy volunteers.
Made available in DSpace on 2018-05-10T01:05:15Z (GMT). No. of bitstreams: 1
ART17061.pdf: 721244 bytes, checksum: 1371a5f86efb5f7be7467bf65fb8a27c (MD5)
Previous issue date: 2018-01-08bitstream/item/170563/1/ART17061.pd
Genomic Expansion of Magnetotactic Bacteria Reveals an Early Common Origin of Magnetotaxis with Lineage-specific Evolution
The origin and evolution of magnetoreception, which in diverse prokaryotes and protozoa is known as magnetotaxis and enables these microorganisms to detect Earth’s magnetic field for orientation and navigation, is not well understood in evolutionary biology. The only known prokaryotes capable of sensing the geomagnetic field are magnetotactic bacteria (MTB), motile microorganisms that biomineralize intracellular, membrane-bounded magnetic single-domain crystals of either magnetite (Fe3O4) or greigite (Fe3S4) called magnetosomes. Magnetosomes are responsible for magnetotaxis in MTB. Here we report the first large-scale metagenomic survey of MTB from both northern and southern hemispheres combined with 28 genomes from uncultivated MTB. These genomes expand greatly the coverage of MTB in the Proteobacteria, Nitrospirae, and Omnitrophica phyla, and provide the first genomic evidence of MTB belonging to the Zetaproteobacteria and “Candidatus Lambdaproteobacteria” classes. The gene content and organization of magnetosome gene clusters, which are physically grouped genes that encode proteins for magnetosome biosynthesis and organization, are more conserved within phylogenetically similar groups than between different taxonomic lineages. Moreover, the phylogenies of core magnetosome proteins form monophyletic clades. Together, these results suggest a common ancient origin of iron-based (Fe3O4 and Fe3S4) magnetotaxis in the domain Bacteria that underwent lineage-specific evolution, shedding new light on the origin and evolution of biomineralization and magnetotaxis, and expanding significantly the phylogenomic representation of MTB
- …