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Title: Time Resolved Imaging of Spin Transfer Switching: Beyond theMacro-Spin Concept

Abstract

No abstract prepared.

Authors:
; ; ; ; ; ; ; ; ;
Publication Date:
Research Org.:
COLLABORATION - SSRL
OSTI Identifier:
923334
Report Number(s):
LBNL-60252
Journal ID: ISSN 0031-9007; PRLTAO; R&D Project: CB1102; BnR: KC0302030; TRN: US200804%%994
DOE Contract Number:
DE-AC02-05CH11231
Resource Type:
Journal Article
Resource Relation:
Journal Name: Physical Review Letters; Journal Volume: 96; Journal Issue: 2; Related Information: Journal Publication Date: 2006
Country of Publication:
United States
Language:
English
Subject:
36; SPIN; TIME RESOLUTION; IMAGES; SPIN EXCHANGE; advanced light source als

Citation Formats

Acremann, Y., Strachan, J.P., Chembrolu, V., Andrews, S.D., Tyliszczak, T., Katine, J.A., Carey, M.J., Clemens, B.M., Siegmann, H.C., and Stohr, J.. Time Resolved Imaging of Spin Transfer Switching: Beyond theMacro-Spin Concept. United States: N. p., 2007. Web.
Acremann, Y., Strachan, J.P., Chembrolu, V., Andrews, S.D., Tyliszczak, T., Katine, J.A., Carey, M.J., Clemens, B.M., Siegmann, H.C., & Stohr, J.. Time Resolved Imaging of Spin Transfer Switching: Beyond theMacro-Spin Concept. United States.
Acremann, Y., Strachan, J.P., Chembrolu, V., Andrews, S.D., Tyliszczak, T., Katine, J.A., Carey, M.J., Clemens, B.M., Siegmann, H.C., and Stohr, J.. Mon . "Time Resolved Imaging of Spin Transfer Switching: Beyond theMacro-Spin Concept". United States. doi:.
@article{osti_923334,
title = {Time Resolved Imaging of Spin Transfer Switching: Beyond theMacro-Spin Concept},
author = {Acremann, Y. and Strachan, J.P. and Chembrolu, V. and Andrews, S.D. and Tyliszczak, T. and Katine, J.A. and Carey, M.J. and Clemens, B.M. and Siegmann, H.C. and Stohr, J.},
abstractNote = {No abstract prepared.},
doi = {},
journal = {Physical Review Letters},
number = 2,
volume = 96,
place = {United States},
year = {Mon May 07 00:00:00 EDT 2007},
month = {Mon May 07 00:00:00 EDT 2007}
}
  • No abstract prepared.
  • Time-resolved x-ray imaging techniques have recently demonstrated the capability to probe the magnetic switching of nanoscale devices. This technique has enabled, for example, the direct observation of the nonuniform intermediate states assumed by the magnetic free layer during reversal by a spin-polarized current. These experiments have shown an interesting size-dependent behavior associated with the motion of vortices to mediate the magnetization reversal which cannot be explained by the macrospin picture of spin-torque switching. In this paper we present both experimental and analytical results which show the origin of the complex switching behavior. We use time-resolved x-ray microscopy to further studymore » the switching behavior of samples with 45{sup o} angle between the free and polarizing magnetic layers. A model is developed in terms of a linearized Landau-Lifshitz-Gilbert equation showing that the initial dynamics is dominated by the balance between the Oersted field and thermal fluctuations. The spin torque amplifies this dynamics, leading to a strong sensitivity to sample size, angle, and temperature. The model is in good agreement with current and previous experimental observations.« less
  • The charge transfer (CT) excited states of Ru(II)OEP(Py){sub 2} and Ru(II)TPP(Py){sub 2} (TPP=tetraphenylporphyrin, OEP=octaethylporphyrin, and Py=pyridine) have been investigated by nanosecond time-resolved resonance Raman(TR{sup 3}) spectroscopy. The spectra reveal unexpected differences between the two species. The TR{sup 3} spectrum of [Ru(II)TPP(Py){sub 2}]{sup *} resembles the resonance Raman (RR) spectrum of the RuTPP(Py){sub 2} radical anion. Both spectra show strong enhancement of nontotally symmetric modes, resulting from a Jahn-Teller distortion due to the e{sub g}{sup *} orbital degeneracy. The band frequencies are slightly higher in the CT state than in the radical anion, reflecting the effect of the Ru(II) oxidation. Thus,more » the TR{sup 3} spectral features support a {sup 3}(d{pi},{pi}{sup *}) excited state assignment, with an electron transferred from Ru(II) to the porphyrin. In contrast, the TR3 spectrum [Ru(II)OEP(Py){sub 2}]{sup *} does not resemble the RR spectra of the Ru(II)OEP radical anion. Rather, it contains totally symmetric modes, at frequencies close to those of Ru(II)OEP(Py){sub 2}. In addition, bound pyridine modes appear at 1208 and 1603 cm{sup -1} in the TR{sup 3} spectrum and they shift upon pyridine perdeuteration. These characteristics imply electron transfer from Ru(II) to bound pyridine, instead of porphyrin, for the CT state of Ru(II)OEP(Py){sub 2}. 38 refs., 11 figs., 4 tabs.« less
  • Time-resolved imaging is carried out to study the dynamics of the laser-induced forward transfer of an aqueous solution at different laser fluences. The transfer mechanisms are elucidated, and directly correlated with the material deposited at the analyzed irradiation conditions. It is found that there exists a fluence range in which regular and well-defined droplets are deposited. In this case, laser pulse energy absorption results in the formation of a plasma, which expansion originates a cavitation bubble in the liquid. After the further expansion and collapse of the bubble, a long and uniform jet is developed, which advances at a constantmore » velocity until it reaches the receptor substrate. On the other hand, for lower fluences no material is deposited. In this case, although a jet can be also generated, it recoils before reaching the substrate. For higher fluences, splashing is observed on the receptor substrate due to the bursting of the cavitation bubble. Finally, a discussion of the possible mechanisms which lead to such singular dynamics is also provided.« less
  • Using a noninvasive, electro-optically based electron bunch arrival time measurement at FLASH (free electron laser in Hamburg) the temporal resolution of two-color pump-probe experiments has been significantly improved. The system determines the relative arrival time of the extended ultraviolet pulse of FLASH and an amplified Ti:sapphire femtosecond-laser pulse at the interaction region better than 90 fs rms. In a benchmarking pump-probe experiment using two-color above threshold ionization of noble gases, an enhancement in the timing resolution by a factor of 4 compared to the uncorrected data is obtained.