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4D Lorentz Electron Microscopy Imaging: Magnetic Domain Wall Nucleation, Reversal, and Wave Velocity

Park, Hyun Soon and Baskin, J. Spencer and Zewail, Ahmed H. (2010) 4D Lorentz Electron Microscopy Imaging: Magnetic Domain Wall Nucleation, Reversal, and Wave Velocity. Nano Letters, 10 (9). pp. 3796-3803. ISSN 1530-6984. https://resolver.caltech.edu/CaltechAUTHORS:20100920-101837410

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Abstract

Magnetization reversal is an important topic of research in the fields of both basic and applied ferromagnetism. For the study of magnetization reversal dynamics and magnetic domain wall (DW) motion in ferromagnetic thin films, imaging techniques are indispensable. Here, we report 4D imaging of DWs by the out-of-focus Fresnel method in Lorentz ultrafast electron microscopy (UEM), with in situ spatial and temporal resolutions. The temporal change in magnetization, as revealed by changes in image contrast, is clocked using an impulsive optical field to produce structural deformation of the specimen, thus modulating magnetic field components in the specimen plane. Directly visualized are DW nucleation and subsequent annihilation and oscillatory reappearance (periods of 32 and 45 ns) in nickel films on two different substrates. For the case of Ni films on a Ti/Si_(3)N_4 substrate, under conditions of minimum residual external magnetic field, the oscillation is associated with a unique traveling wave train of periodic magnetization reversal. The velocity of DW propagation in this wave train is measured to be 172 m/s with a wavelength of 7.8 μm. The success of this study demonstrates the promise of Lorentz UEM for real-space imaging of spin switching, ferromagnetic resonance, and laser-induced demagnetization in ferromagnetic nanostructures.


Item Type:Article
Related URLs:
URLURL TypeDescription
http://dx.doi.org/10.1021/nl102861eDOIArticle
http://pubs.acs.org/doi/abs/10.1021/nl102861ePublisherArticle
http://pubs.acs.org/doi/suppl/10.1021/nl102861ePublisherSupporting Information
Additional Information:© 2010 American Chemical Society. Received for review: 08/12/2010; published on Web: 08/25/2010. This work was supported by the National Science Foundation and Air Force Office of Scientific Research in the Gordon and Betty Moore Center for Physical Biology at Caltech.
Funders:
Funding AgencyGrant Number
NSFUNSPECIFIED
Air Force Office of Scientific Research (AFOSR)UNSPECIFIED
Gordon and Betty Moore FoundationUNSPECIFIED
Subject Keywords:4D imaging; magnetic domain dynamics; ultrafast electron microscopy; ferromagnetic materials
Issue or Number:9
Record Number:CaltechAUTHORS:20100920-101837410
Persistent URL:https://resolver.caltech.edu/CaltechAUTHORS:20100920-101837410
Official Citation:4D Lorentz Electron Microscopy Imaging: Magnetic Domain Wall Nucleation, Reversal, and Wave Velocity Hyun Soon Park, J. Spencer Baskin, Ahmed H. Zewail Nano Letters 2010 10 (9), 3796-3803
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:20041
Collection:CaltechAUTHORS
Deposited By: Jason Perez
Deposited On:24 Sep 2010 21:47
Last Modified:03 Oct 2019 02:05

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