Discovery[change | change source]
GMR was discovered in layers iron, chrome and ferrite by Peter Grünbergs research team of the Jülich Research Centre (Germany) in 1988. Peter Grünberg owns a patent for the technology. It was also discovered by Albert Ferts research group of the University of Paris-Sud (France) in layers ferrite and chrome. The Fert group were first to see what they thought of as a large effect which is why they gave the name "Giant". The Fert group were also first to explain the correct physics of GMR. The discovery was the beginning of the science spintronics. Grünberg and Fert have been given prizes and awards, including the 2007 Nobel Prize in Physics, for this discovery and other spintronics work.
Types of GMR[change | change source]
Multilayer GMR[change | change source]
In multilayer GMR, two or more magnetic layers are separated by a very thin (about 1 nm) non-magnetic (insulating) layer. Ferrite, a form of iron, is a magnetic layer and chrome is an insulating layer. At certain thicknesses, the strength of magnetism between the layers becomes easy to measure and adjust. The strength of electrical current between the layers can change by up to 10%.
The GMR effect was first observed in stacks of 10 or more layers.
Spin valve GMR[change | change source]
It is hoped that research into spinning electrons will improve spin valves.
Granular GMR[change | change source]
Granular GMR is an effect found in copper containing grains of cobalt. It is not possible to control the strength of granular GMR in the same manner as Multilayer GMR.
Use of GMR[change | change source]
GMR is used in modern hard drives and magnetic sensors. Another use of the GMR effect is in magnetoresistive random access memory (MRAM). GMR has begun a new science of electronics called spintronics.
References[change | change source]
- L. L. Hinchey and D. L. Mills (1986). "Magnetic properties of superlattices formed from ferromagnetic and antiferromagnetic materials". Physical Review B 33 (5): 3329–3343. doi:10.1103/PhysRevB.33.3329. http://link.aps.org/abstract/PRB/v33/p3329.
- P. Grünberg, R. Schreiber, Y. Pang, M. B. Brodsky, and H. Sowers (1986). "Layered Magnetic Structures: Evidence for Antiferromagnetic Coupling of Fe Layers across Cr Interlayers". Physical Review Letters 57 (19): 2442–2445. doi:10.1103/PhysRevLett.57.2442. http://link.aps.org/abstract/PRL/v57/p2442.
- C. Carbone and S. F. Alvarado (1987). "Antiparallel coupling between Fe layers separated by a Cr interlayer: Dependence of the magnetization on the film thickness". Physical Review B 36 (4): 2433. doi:10.1103/PhysRevB.36.2433. http://link.aps.org/abstract/PRB/v36/p2433.
- M. N. Baibich, J. M. Broto, A. Fert, F. Nguyen Van Dau, F. Petroff, P. Eitenne, G. Creuzet, A. Friederich, and J. Chazelas (1988). "Giant Magnetoresistance of (001)Fe/(001)Cr Magnetic Superlattices". Physical Review Letters 61 (21): 2472–2475. doi:10.1103/PhysRevLett.61.2472. http://link.aps.org/abstract/PRL/v61/p2472.
- G. Binasch, P. Grünberg, F. Saurenbach, and W. Zinn (1989). "Enhanced magnetoresistance in layered magnetic structures with antiferromagnetic interlayer exchange". Physical Review B 39 (7): 4828–4830. doi:10.1103/PhysRevB.39.4828. http://link.aps.org/abstract/PRB/v39/p4828.
- A. E. Berkowitz, J. R. Mitchell, M. J. Carey, A. P. Young, S. Zhang, F. E. Spada, F. T. Parker, A. Hutten, and G. Thomas (1992). "Giant magnetoresistance in heterogeneous Cu-Co alloys". Physical Review Letters 68 (25): 3745–3748. doi:10.1103/PhysRevLett.68.3745. http://link.aps.org/abstract/PRL/v68/p3745.
- John Q. Xiao, J. Samuel Jiang, and C. L. Chien (1992). "Giant magnetoresistance in nonmultilayer magnetic systems". Physical Review Letters 68 (25): 3749–3752. doi:10.1103/PhysRevLett.68.3749. http://link.aps.org/abstract/PRL/v68/p3749.
- Z.Y. Leong, S.G. Tan, M.B.A. Jalil, S. Bala Kumar, and G.C. Han (Journal of Magnetism and Magnetic Materials). "Magnetoresistance modulation due to interfacial conductance of current perpendicular-to-plane spin valves". Journal of Magnetism and Magnetic Materials 310 (2): e635–637. doi:10.1016/j.jmmm.2006.10.679.
Other pages[change | change source]
Other websites[change | change source]
- Giant Magnetoresistance: The Really Big Idea Behind a Very Tiny Tool National High Magnetic Field Laboratory
- Presentation of GMR-technique (IBM Research)
- Nobel prize in physics 2007 - Scientific background
- Scientific background