NIMS Award Winner: William H. Butler,

Professor, Center for Materials for Information Technology (MINT), University of Alabama



An achievement in Materials Science and Technology:

gTheoretical prediction of giant tunnel magnetoresistance in Fe/MgO/Fe junctionh



Curriculum vitae:


Prof. William H. Butler was appointed as the Director of the MINT Center in August 2001 and is a Professor of Physics in the Department of Physics and Astronomy. He also serves as director of the NSF-sponsored Materials Research Science and Engineering Center. He received a BS degree (with Highest Honors) in Physics from Auburn University in 1960 and a Ph.D. in physics in 1969 from the University of California, San Diego where he studied under Professor Walter Kohn. From 1969 until 1972 he was Assistant Professor of Physics at Auburn University. He joined the Metals and Ceramics Division of Oak Ridge National Laboratory in 1972, where he was group leader of the Theory Group from 1984 to 2001. He has received DOE Awards for Outstanding Scientific Achievement and for Outstanding Sustained Research. He has authored more than 30 papers on transport and giant magnetoresistance as well as more than 125 papers on the electronic and magnetic structure of transition metals and alloys. He is a member of the American Physical Society, the Materials Research Society, and the American Association for the Advancement of Science. He is a fellow of the American Physical Society. He served as Meeting Chair for the Spring 1990 Meeting of the MRS.



Brief introduction of Prof. Butlerfs achievements:


In magnetic recording technology, writing and reading on magnetic media become increasingly difficult as storage capacity increases. In particular, the reading technique requires higher sensitivity and resolution, so magnetic tunnel junctions are now being studied and have entered practical use. These junctions are also used for non-volatile magnetic random access memory (MRAM). An amorphous insulator such as Al2O3 was traditionally used for magnetic tunnel junctions. However, Prof. Butler carried out a first-principles calculation for the tunneling transport through MgO(001) single-crystal thin film, and theoretically predicted giant tunnel magnetoresistance (TMR) in the Fe/MgO/Fe (001) junction. Specifically, he predicted coherent tunneling transport through the MgO(001) layer, which leads to the giant TMR, increase in TMR with MgO thickness, oscillation of TMR as a function of MgO thickness, etc. These results were reported in Physical Review B, 2001. In succeeding years, both Dr. Yuasa of AIST and Dr. Perkin of IBM studied the thin film system around almost the same time (2004), and reported giant TMR of 180% and 220% at room temperature. These performances proved the validity of Prof. Butlerfs theoretical predictions, and TMR exceeding 500% has now been achieved. This rapid improvement is expected to provide high functionality for spintronics devices and lead to new applications. We recognize Prof. Butlerfs outstanding achievements which have paved the way for breakthroughs in magnetic recording materials.

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Professor William H. Butler  (the University of Alabama)