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Physics

Magnetics

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Displaying 101 - 125 of 153

On-wafer Magnetic Resonance of Magnetite Nanoparticles

May 11, 2015
Author(s)
Charles A. Little, Stephen E. Russek, James C. Booth, Pavel Kabos, Robert J. Usselman
Magnetic resonance measurements of ferumoxytol and TEMPO were made using an on-wafer transmission line technique with a vector network analyzer, allowing for broadband measurements of small sample volumes (4 nl) and a small numbers of spin (1 nmole). On

Nanoscale Spin Valve Josephson Junction Devices

April 14, 2015
Author(s)
Burm Baek, William H. Rippard, Matthew R. Pufall, Samuel P. Benz, Stephen E. Russek, Horst Rogalla, Paul D. Dresselhaus
Traditionally, superconductivity and magnetism have had a mutually exclusive relationship. However, the physics of superconductor-ferromagnet hybrid structures turned out to be far from being simply destructive, which has led to the hope of a new breed of

Nonlinear ferromagnetic resonance shift in submicron Permalloy ellipses

February 27, 2015
Author(s)
Feng Guo, Lyubov Belova, Robert D. McMichael
We report a systematic study of nonlinearity in the ferromagnetic resonance of a series of submicron Permalloy ellipses with varying aspect ratios. We focus on the sign of the foldover, a resonance field shift or frequency shift that occurs with high

Magnetic structure and anisotropy of [Co/Pd]_5/NiFe multilayers

January 9, 2015
Author(s)
Larysa Tryputen, Feng Guo, Liu Frank, T. N. Anh Nguyen, Majid Mohseni, Sunjae Chung, Yeyu Fang, Johan Akerman, Robert McMichael, Caroline Ross
The magnetization behavior, magnetic anisotropy and domain congurations of Co/Pd multilayers with perpendicular magnetic anisotropy capped with permalloy is investigated using magnetometry, magnetic force microscopy and ferromagnetic resonance. The

Spin-transfer torque switching observed in nanopillar superconducting-magnetic hybrid Josephson junctions

January 9, 2015
Author(s)
Burm Baek, William H. Rippard, Matthew R. Pufall, Samuel P. Benz, Stephen E. Russek, Horst Rogalla, Paul D. Dresselhaus
Combining superconducting and magnetic materials to create novel superconducting devices has been motivated by the discovery of the Josephson critical current (Ics) oscillations with magnetic layer thickness and the demonstration of devices with switchable

Phase-Sensitive Detection of Spin Pumping via the ac Inverse Spin Hall Effect

October 6, 2014
Author(s)
Thomas J. Silva, Justin M. Shaw, Hans T. Nembach, Mathias A. Weiler
Sources of pure spin currents are a fundamental building block of spintronic devices. In ferromagnet/normal metal heterostructures, spin currents are generated at ferromagnetic resonance. This is known as spin pumping, where spin currents of both dc and ac

Interface Engineering to Control Magnetic Field Effects of Organic-Based Devices by Using a Molecular Self-Assembled Monolayer

June 26, 2014
Author(s)
Hyuk-Jae Jang, Sujitra J. Pookpanratana, Alyssa N. Brigeman, Regis J. Kline, James I. Basham, David J. Gundlach, Christina A. Hacker, Oleg A. Kirillov, Oana Jurchescu, Curt A. Richter
Organic semiconductors hold immense promise for the development of a wide range of innovative devices with their excellent electronic and manufacturing characteristics. Of particular interest are non-magnetic organic semiconductors that show unusual

Correlation of anomalous write error rate and ferromagnetic resonance spectrum in spin-transfer-torque-magnetic-random-access-memory devices containing in-plane free layers

May 28, 2014
Author(s)
Eric R. Evarts, Ranko R. Heindl, William H. Rippard, Matthew R. Pufall
In a small fraction of magnetic-tunnel-junction-based MRAM devices with in-plane free layers, the write error rates (WERs) are higher than expected on the basis of the macrospin or quasi-uniform magnetization reversal models. In devices with increased WERs

Hybrid superconducting-magnetic memory device using competing order parameters

May 28, 2014
Author(s)
Burm Baek, William H. Rippard, Samuel P. Benz, Stephen E. Russek, Paul D. Dresselhaus
The quantum behavior of Josephson junctions is often exploited to produce superconducting devices with outstanding performance. Josephson junctions can also be used in circuits that perform logic operations in picoseconds and may enable high-performance

Parametric pumping of precession modes in ferromagnetic nanodisks

March 26, 2014
Author(s)
Feng Guo, Lyubov Belova, Robert McMichael
We report parametric excitation of magnetic precession modes in nanodisks using a parallel pumping configuration. The excitations are detected using a ferromagneitc resonance force microscopy method, and the parallel-pumped spectra reveal nonlinear

Comment on Detection of Microwave Spin Pumping Using the Inverse Spin Hall Effect

January 27, 2014
Author(s)
Thomas J. Silva, Mathias A. Weiler, Hans T. Nembach, Justin M. Shaw
In a recent Letter, Hahn et al. reported on the detection of an ac voltage in a yttrium iron garnet (YIG)/platinum (Pt) bilayer under the condition of parametrically excited resonance. The authors observe an ac voltage at the frequency of the magnetization

State and Measurement Tomography of an Exchange-Only Spin Qubit

September 1, 2013
Author(s)
Jacob M. Taylor, Medford Jim, Johannes Beil, Stephen Bartlett, Andrew Doherty, Emmanuel Rashba, David P. DiVincenzo, H Lu, A. C. Gossard
We demonstrate the initialization, full electrical control, and state tomography of an exchange- only spin qubit in a GaAs heterostructure. Decoherence and leakage from the qubit subspace are accounted for with a model of charge noise and fluctuating

Electrically-protected resonant exchange qubits in triple quantum dots

July 31, 2013
Author(s)
Jacob M. Taylor, Vanita Srinivasa, Medford Jim
We present a modulated microwave approach for quantum computing with qubits comprising three spins in a triple quantum dot. This approach includes single- and two-qubit gates that are protected against low-frequency electrical noise, due to an operating

The Resonant Exchange Qubit

July 31, 2013
Author(s)
Jacob M. Taylor, Medford Jim, Johannes Beil, Emmanuel Rashba, H Lu, A. C. Gossard, C. M. Marcus
We introduce a solid-state qubit in which exchange interactions among confined electrons provide both the static longitudinal field and the oscillatory transverse field, allowing rapid and full qubit control via rf gate-voltage pulses. We demonstrate two

Properties of magnetic barrier structures for superconducting-magnetic hybrid Josephson junctions

July 7, 2013
Author(s)
Burm Baek, Samuel P. Benz, William H. Rippard, Stephen E. Russek, Paul D. Dresselhaus, Horst Rogalla, Matthew R. Pufall
If Josephson and spintronic technologies can be successfully integrated to produce a cryogenic memory that can be controlled with single-flux quantum pulses, then they may enable ultra-low-power, high-speed computing. We have developed hybrid Josephson

Spin-Transfer Nano-Oscillators

January 7, 2013
Author(s)
Stephen E. Russek, Ranko R. Heindl, Thomas Cecil, William H. Rippard
Spin transfer nano-oscillators are small multilayer magnetic devices that undergo microwave oscillations and output a microwave voltage when a bias current is applied. The oscillation frequency is tunable, over a range of 0.5 GHz to 225 GHz, by varying the

Spectroscopy and imaging of edge modes in Permalloy nanodisks

January 3, 2013
Author(s)
Feng Guo, Lyubov Belova, Robert McMichael
This paper reports spectroscopy and imaging of spin wave modes using ferromagnetic resonance force microscopy (FMRFM) in Permalloy nano-disks with disk diameters that range from 100 nm to 750 nm. The ferromagnetic resonance spectra distinguish multiple

Two dimensional spectroscopic imaging of individual ferromagnetic nanostripes

November 6, 2012
Author(s)
Han-Jong H. Chia, Feng Guo, Lyubov Belova, Robert McMichael
We use ferromagnetic resonance force microscopy (FMRFM) to spectroscopically image the edge modes in individual 700 and 400 nm wide Permalloy stripes with a spatial resolution on the order of 200 nm. The imaging clearly identi es some resonances as edge

Microwave Behavior of polymer bonded Iron oxide nanoparticles

November 1, 2012
Author(s)
Pavel Kabos, A Caprile, Coisson Marco, F Fiorillo, O M. Manu, E. S. Olivetti, M. A. Olariu, Pasquale Massimo, V. A. Scarlatache
Samples composed of a polymer matrix were loaded with different fractions from 0 to 30% of Fe oxide magnetic nanoparticles with an average size ranging from 50 to 25 nm. The permittivity and permeability of the composites were determined upon a very wide

Observation of spin-valve effect in Alq3 using a low work function metal

September 7, 2012
Author(s)
Hyuk-Jae Jang, Kurt Pernstich, David J. Gundlach, Oana Jurchescu, Curt A. Richter
We present the observation of magnetoresistance in Co/Ca/Alq3/Ca/NiFe spin-valve devices. Thin Ca layers contacting 150 nm thick Alq3 enable the injection of spin-polarized electrons into Alq3 due to engineering of the band alignment. The devices exhibit
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