Nanocrystalline materials can possess bulk properties quite different from those commonly associated with conventional large-grained materials. Nanocomposites, a subset of nanocrystalline materials, in addition have been found to possess magnetic properties which are similar to, but different from, the properties of the individual constituents. New magnetic phenomena, unusual property combinations, and both enhanced and diminished magnetic property values are just some of the changes observed in magnetic nanocomposites from conventional magnetic materials. Here, a description will be presented of some of the exciting new properties discovered in nanomaterials and the magnetic applications envisioned for them. Particular attention will be devoted to three world-leading activities in this area at NIST being pursued in the Magnetic Materials Group: the preparation of GMR spin valves having the world's highest MR values with the smallest switching fields, the prediction and discovery of the Enhanced Magnetocaloric Effect in magnetic nanocomposites, and the development and application to magnetic exchange-biased films of the Magneto-Optic Imaging Film (MOIF) technique for magnetic domain imaging. These activities are assisting the rapid development of ultra-high density magnetic recording media, high temperature magnetic refrigerators, and controllable magnetic switches.
Robert D. Shull received a S.B. in Materials Science from MIT in 1968, and a M.S. and Ph.D. in the same field from the University of Illinois at Urbana-Champaign in 1973 and 1976 respectively. His PhD thesis work, in which he discovered the reversed Curie temperature phenomenon in Fe70Al30, was instrumental in his recent discovery of a Spin Density Wave (a phenomenon which had been predicted 40 years ago to exist, but never found) in the same alloy system. After being awarded a postdoctoral fellowship from CALTECH during 1976-1979, he joined the National Bureau of Standards where he initially set up the rapid solidification facility that led to the discovery of quasicrystals in 1980. Dr. Shull was also part of the collaboration that prepared the first thin films of a high TC superconductor by the laser ablation process (awarded Best Paper of the Year at the Applied Physics Laboratory of JHU), and his field ion microscopy observation of the high TC materials (first ever) was even featured on the cover of Science magazine (Jan. 8, 1988). He was the first to explain the novel attractable levitation found in some high TC materials, and he discovered the enhanced magnetocaloric effect in nanocomposites.
Dr. Shull has authored and co-authored over 140 publications and presented over 200 invited talks. He has been a member of the International Committee on Nanostructured Materials (ICNM) since 1990, and was its Chairman from 1999-2001. He was also a founding member of the OSTP subcommittee on Nanoscale Science, Engineering and Technology (NSET), the group which drafted the original National Nanotechnology Initiative (NNI) in 2001. Dr. Shull has been awarded several NIST Director's Innovation and Competence Awards, the NIST EEO/Diversity Award, and the Outstanding Service Award by the NIST Chapter of Sigma Xi. He has also led a 6-month long pre-high school science program, called Adventure In Science, for the past 18 years. He is presently the Group Leader of the Magnetic Materials Group at NIST. Dr. Shull is also the son of Dr. Clifford G. Shull, the winner of the 1994 Nobel Prize in Physics.
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