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Giant magnetoresistive heterogeneous alloys and method of making same

United States Patent

March 16, 1999
View the Complete Patent at the US Patent & Trademark Office
Lawrence Berkeley National Laboratory - Visit the Technology Transfer and Intellectual Property Management Department Website
The inventive material exhibits giant magnetoresistance upon application of an external magnetic field at room temperature. The hysteresis is minimal. The inventive material has a magnetic phase formed by eutectic decomposition. The bulk material comprises a plurality of regions characterized by a) the presence of magnetic lamellae wherein the lamellae are separated by a distance smaller than the mean free path of the conduction electrons, and b) a matrix composition having nonmagnetic properties that is interposed between the lamellae within the regions. The inventive, rapidly quenched, eutectic alloys form microstructure lamellae having antiparallel antiferromagnetic coupling and give rise to GMR properties. The inventive materials made according to the inventive process yielded commercially acceptable quantities and timeframes. Annealing destroyed the microstructure lamellae and the GMR effect. Noneutectic alloys did not exhibit the antiparallel microstructure lamellae and did not possess GMR properties.
Bernardi; Johannes J. (Berkeley, CA), Thomas; Gareth (Oakland, CA), Huetten; Andreas R. (Berkeley, CA)
The Regents of the University of California (Oakland, CA)
08/ 978,436
November 25, 1997
This invention was made with U.S. Government support under Contract No. DE-AC03-76SF00098 between the U.S. Department of Energy and the University of California for the operation of Lawrence Berkeley Laboratory. The U.S. Government may have certain rights in this invention.