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Magnetization dynamics of irradiation-fabricated perpendicularly magnetized dots inside a softer magnetic matrix

Published online by Cambridge University Press:  15 February 2011

T. Devolder ,
M. Belmeguenai ,
C. Chappert ,
H. Bernas  and
Y. Suzuki
T. Devolder
Affiliation:
Institut d'Electronique Fondamentale, UMR CNRS 8622, Université Paris-Sud, 91405 Orsay, FRANCE.
M. Belmeguenai
Affiliation:
Institut d'Electronique Fondamentale, UMR CNRS 8622, Université Paris-Sud, 91405 Orsay, FRANCE.
C. Chappert
Affiliation:
Institut d'Electronique Fondamentale, UMR CNRS 8622, Université Paris-Sud, 91405 Orsay, FRANCE.
H. Bernas
Affiliation:
Centre de Spectrométrie Nucléaire et de Spectrométrie de Masse, UMR CNRS 8609, Université Paris-Sud, Orsay, FRANCE.
Y. Suzuki
Affiliation:
National Institute of Advanced Industrial Science and Technology, Electronics Institute, Tsukuba, JAPAN.
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Abstract

Global Helium ion irradiation can tune the magnetic properties of thin films, notably their magneto-crystalline anisotropy. Helium ion irradiation through nanofabricated masks can been used to produce sub-micron planar magnetic nanostructures of various types. Among these, perpendicularly magnetized dots in a matrix of weaker magnetic anisotropy are of special interest because their quasi-static magnetization reversal is nucleation-free and proceeds by a very specific domain wall injection from the magnetically “soft” matrix, which acts as a domain wall reservoir for the “hard” dot. This guarantees a remarkably weak coercivity dispersion. This new type of irradiation-fabricated magnetic device can also be designed to achieve high magnetic switching speeds, typically below 100 ps at a moderate applied field cost. The speed is obtained through the use of a very high effective magnetic field, and high resulting precession frequencies. During magnetization reversal, the effective field incorporates a significant exchange field, storing energy in the form of a domain wall surrounding a high magnetic anisotropy nanostructure's region of interest. The exchange field accelerates the reversal and lowers the cost in reversal field. Promising applications to magnetic storage are anticipated.

Type
Research Article
Information
MRS Online Proceedings Library (OPL) , Volume 777: Symposium A – Nanostructuring Materials with Energetic Beams , 2003 , T6.4
Copyright
Copyright © Materials Research Society 2003

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