Correlation of edge roughness to nucleation field and nucleation field distribution in patterned Permalloy elements

J. W. Lau and R. D. McMichael

Metallurgy Division, National Institute of Standards and Technology, Gaithersburg, MD 20899

M. A. Schofield and Y. Zhu

Center for Functional Nanomaterials, Brookhaven National Laboratory, Upton, NY 11973

For magnetic devices, the trend toward nanostructures increases the boundary-to-volume Ratio and emphasizes the role of edges on switching behavior in applications such as magnetic memory chips and patterned-media hard drives.  For both technologies, the `bits' are nano-islands of magnetic material that ideally have identical switching fields.  In reality, however, there exists a switching-field distribution (SFD) due to subtle differences among the bits on the Nanoscale. Understanding the origin of SFDs is important because a broad SFD reduces both bit density and memory reliability. In this work, we examine edge roughness as a nanoscale non-uniformity, and find direct correlations to both the switching field and the SFD for switching by vortex nucleation. These results bridge an important gap in the understanding of how physical edge attributes alter switching behavior, providing guidelines for the design of new high-density data storage devices.

 

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Name:              June Lau

Mentor:            Robert McMichael

Laboratory:      MSEL

Room:              B142

Building:           223

Mail Stop         8552

Telephone #:     x5711

FAX #: x4553

Email:              june.lau@nist.gov

Category:         Physics

 

Not a Sigma Xi member.