4,230 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
Phase locking dynamics of dipolarly coupled vortex-based spin transfer oscillators
Phase locking dynamics of dipolarly coupled vortices excited by
spin-polarized current in two identical nanopillars is studied as a function of
the interpillar distance L. Numerical study and analytical model have proved
the remarkable efficiency of magneto-static interaction to achieve phase
locking. Investigating the dynamics in the transient regime towards phase
locking, we extract the evolution of the locking time \tau, the coupling
strength {\mu} and the interaction energy W. Finally, we compare this coupling
energy with the one obtained by simple model.Comment: 4 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
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
Caracterização do pó da casca de coco verde usado como substrato agrícola.
O aumento do consumo de agua-de-coco verde e a vocacao natural para sua industrializacao vem causando problema de disposicao final do residuo gerado, ou seja, as cascas do fruto. A analise do comportamento historico da oferta de coco verde no mercado demonstra crescimento significativo.bitstream/CNPAT-2010/5862/1/Ct-054.pd
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
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