Field and current induced magnetization reversal in patterned Pseudo Spin Valve devices

The field and current induced magnetization switchings of Pseudo-Spin-Valve (PSV) devices are described in this dissertation. An aligned sequence of three (one optical and two electron-beam) lithographies was used to define the devices and their electrical contacts. The PSV stack comprised a layer of soft ferromagnetic material Ni80oFe20 (NiFe or Py), a non-magnetic spacer layer of Cu, a hard ferromagnetic layer of Co and a capping layer of Au. The current flowed in plane (CIP) and the devices displayed giant magnetoresistance (GMR). Three different shapes were investigated: notched bars, elliptical rings and rhomboidal rings. In the bars, the notches provided strong pinning potential wells for transverse domain walls in the NiFe layer, which, upon cycling an external field, reversed in a step-like fashion, with domain walls nucleating from both ends of the bars, due to strong magnetostatic coupling between both magnetic layers. Additional important magnetostatic coupling effects were measured and micromagnetic simulations confirmed the ubiquity of such coupling. Current induced magnetic switching (CIMS) experiments were conducted, and threshold densities of the order of 1011 A/m2 were used to switch the magnetization under an external bias field, and the critical current decreased with increasing bias.

Department dc:contributor.department

Massachusetts Institute of Technology. Dept. of Materials Science and Engineering.

Grantor dc:publisher

Massachusetts Institute of Technology

Year dc:date.issued

2007

Author dc:creator

• Colin, Irénée A. (Irénée Anthelme)

Advisor dc:contributor.advisor

• Caroline A. Ross.

• Materials Science and Engineering.

Statement dc:rights

• M.I.T. theses are protected by copyright. They may be viewed from this source for any purpose, but reproduction or distribution in any format is prohibited without written permission. See provided URL for inquiries about permission.

Licence dc:rights.uri

• http://dspace.mit.edu/handle/1721.1/7582

Language dc:language.iso

eng

Handle dc:identifier.uri

http://hdl.handle.net/1721.1/39546

OAI identifier oai:identifier

oai:dspace.mit.edu:1721.1/39546