Abstract
We use off-axis electron holography in the transmission electron microscope (TEM) to study magnetic flux closure (FC) states in self-assembled nanoparticle rings that each contain between five and eleven 25-nm-diameter Co crystals. Electron holograms are acquired at room temperature in zero-field conditions after applying chosen magnetic fields to the samples in situ in the TEM by partially exciting the conventional microscope objective lens. Mean inner potential contributions to the phase shift are determined by turning the samples over, and subsequently subtracted from each recorded phase image to obtain magnetic induction maps. Our results show that most nanoparticle rings form FC remanent magnetic states, and occasionally onion-like states. Although the chiralities (the directions of magnetization) of the FC states are determined by the shapes, sizes and positions of the constituent nanoparticles, reproducible magnetization reversal of each ring can be achieved by using an out-of-plane magnetic field of between 1600 and 2500 Oe.
This is a preview of subscription content, log in via an institution to check access.
Similar content being viewed by others
References
J-G. Zhu, Y. Zheng, and G.A. Prinz, J. Appl. Phys. 87, 6668–6673 (2000).
M. Kläui, J. Rothman, L. Lopez-Diaz, C.A.F. Vaz, J.A.C. Bland, and Z. Cui, Appl. Phys. Lett. 78, 3268–3270 (2001).
J. Rothman, M. Kläui, L. Lopez-Diaz, C.A.F. Vaz, A. Bleloch, J.A.C. Bland, Z. Cui, and R. Speaks, Phys. Rev. Lett. 86, 1098–1101 (2001).
Y.G. Yoo, M. Kläui, C.A.F. Vaz, L.J. Heydeman, and J.A.C. Bland, Appl. Phys. Lett. 82, 2470–2472 (2003).
S.P. Li, D. Peyrade, M. Naltali, A. Lebib, Y. Chen, U. Ebels, L.D. Buda, and K. Ounadjela, Phys. Rev. Lett. 86, 1102–1105 (2001).
S. Sun, C.B. Murray, D. Weller, L. Folks, and A. Moser, Science 287, 1989–1992 (2000).
V.F. Puntes, P. Gorostiza, D.M. Aruguete, N.G. Bastus, and P. Alivisatos, Nature Materials 3, 263–268 (2004).
S.L. Tripp, R.E. Dunin-Borkowski, and A. Wei, Angew. Chem. Int. Ed. 42, 5591–5593 (2003).
S.L. Tripp, S.V. Pusztay, A.E. Ribbe, and A. Wei, J. Am. Chem. Soc. 124, 7914–7915 (2002).
R.E. Dunin-Borkowski, M.R. McCartney, and D.J. Smith, in Encyclopedia of Nanoscience and Nanotechnology, edited by H.S. Nalwa (American Scientific Publisher, 2004), pp.41–100.
Author information
Authors and Affiliations
Rights and permissions
About this article
Cite this article
Kasama, T., Dunin-Borkowski, R.E., Scheinfein, M.R. et al. Off-Axis Electron Holography of Self-Assembled Co Nanoparticle Rings. MRS Online Proceedings Library 1026, 1803 (2007). https://doi.org/10.1557/PROC-1026-C18-03
Received:
Accepted:
Published:
DOI: https://doi.org/10.1557/PROC-1026-C18-03