Microscopic Magnetic Devices

Small, lithographically patterned magnetic structures are used in various ways for information storage, magnetic field sensing, and magnetic device biasing. Controlling the magnetic domain structure in these devices is essential to their operation. SEMPA can be used to see if the domains are behaving as expected.

For example, this figure shows a SEMPA image of the magnetization in a 100 µm Fe test pattern made by the Naval Research Lab. Ideally, the easy magnetization axis of the Fe film, which is grown epitaxially on the GaAs substrate, should be aligned with the sides of the "C" magnet and should be single domain along each leg. Such a magnetization structure would produce a significant magnetic field in the air gap of the "C". This structure would therefore be useful for magnetically biasing small field sensitive devices such as spin transistors or filters that would be located in the gap. SEMPA images of the actual magnetization, however, reveal that, for this geometry and size, these shapes form closure domains at the magnet poles and therefore there is no net magnetic field in the gap.

John Unguris
Robert J. Celotta
Daniel T. Pierce

Michael Kelley - NIST
David Tulchinsky - Naval Research Laboratory

Gary Prinz - Naval Research Laboratory
Conrad Busman - Naval Research Laboratory

Supported in part by the Office of Naval Research

Online: April 1996
Last Updated: February 2008

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