This week, scientists at the National Institute of Standards and Technology (NIST) have joined colleagues around in the world in congratulating Albert Fert of France and Peter Grünberg of Germany for winning the 2007 Nobel Prize in Physics. The pair won for their independent discovery of giant magnetoresistance (GMR), the phenomenon used for reading data on today's high-capacity magnetic disk drives.
NIST has numerous connections to the Nobel Prize winning work and to the study of GMR in general. The Nobel Prize background material* cites papers[1,2] done at the NIST Center for Neutron Research (NCNR), by groups that include Charles Majkrzak, Julie Borchers, and Ross Erwin, all of whom are now part of NIST staff. Then as now, the neutron work takes advantage of the ability of neutrons to determine the detailed microscopic properties of magnetic materials. These scientists and other NIST researchers (including Boulder's Pavel Kabos) collaborated directly with Grünberg on more than seven joint publications.
In addition, many other NIST researchers have advanced the GMR field. NIST researcher William Egelhoff and colleagues set some of the early records for the magnitude of the GMR effect [4-6]; Mark Stiles published an important theoretical contribution that has been cited by other scientists hundreds of times. John Unguris, Bob Celotta, and Dan Pierce uncovered specific characteristics in the structure of magnetic materials that cause the GMR effect. Bill Rippard, Tom Silva and Stephen Russek helped discover new effects that build on the original discovery of GMR. The effect, coupled with GMR, is being used to develop new types of devices for nanoscale signal processing and communication.[9,10]
Other NIST researchers who are working on GMR include the groups associated with Robert McMichael, Ron Goldfarb, Robert Shull, and Michael Donahue. GMR and related effects from the field of spintronics might enable future consumer devices to store even more information than before as they manipulate information through the quantum mechanical property of electrons known as spin.
*The Nobel Prize in Physics 2007 Scientific Background, http://nobelprize.org/nobel_prizes/physics/laureates/2007/phyadv07.pdf.
1. C.F. Majkrzak, J.W. Cable, J. Kwo, M. Hong, D.B. McWhan, Y. Yafet, and J.V. Waszczak, and C. Vettier, Observation of a magnetic antiphase domain structure with long-range order in a synthetic Gd-Y superlattice, Phys. Rev. Lett. 56, 2700 (1986).
2. M.B. Salamon, S. Sinha, J.J. Rhyne, J.E. Cunningham, R.E. Erwin, J. Borchers, and C.P. Flynn, Long-range incommensurate magnetic order in a Dy-Y multilayer, Phys. Rev. Lett. 56, 259 (1986).
3. P. Kabos, W.D. Wilber, C.E. Patton, and P. Grunberg, Brillouin light scattering study of magnon branch crossover in thin iron films, Phys. Rev. B 29, 6396 (1984).
4. W.F. Egelhoff, Jr., T. Ha, R.D.K. Misra, Y. Kadmon, J. Nir, C.J. Powell, M.D. Stiles, R.D. McMichael, C.-L. Lin, J.M. Sivertsen, J.H. Judy, K. Takano, A.E. Berkowitz, T.C. Anthony, and J.A. Brug, Magnetoresistance values exceeding 21% in symmetric spin valves, J. Appl. Phys., 78, 273 (1995).
5. W.F. Egelhoff, Jr., P.J. Chen, C.J. Powell, M.D. Stiles, R.D. McMichael, C.-L. Lin, J.M. Sivertsen, J.H. Judy, K. Takano, A.E. Berkowitz, T.C. Anthony, and J.A. Brug, Optimizing the GMR of symmetric and bottom spin valves, J. Appl. Phys. 79, 5277 (1996).
6. W.F. Egelhoff, Jr., P.J. Chen, C.J. Powell, M.D. Stiles, R.D. McMichael, J.H. Judy, K. Takano,and A.E. Berkowitz, Oxygen as a surfactant in the growth of GMR spin valves, J. Appl. Phys., 82, 6142 (1997).
7. M.D. Stiles, Exchange coupling in magnetic heterostructures, Physical Review B 48, 7238 (1993).
8. J. Unguris, R.J. Celotta, and D.T. Pierce, Observation of two different oscillation periods in the exchange coupling of Fe/Cr/Fe(100), Phys. Rev. Lett. 67, 140-143 (1991).
9. S. Kaka, M.R. Pufall, W.H. Rippard, T.J. Silva, S.E. Russek , and J.A. Katine, Mutual phase-locking of microwave spin torque nano-oscillators, Nature 437, 389-392 (2005).
10. W.H. Rippard, M.R. Pufall, S. Kaka, S.E. Russek, and T.J. Silva, Direct-current induced dynamics in Co90Fe10/Ni80Fe20 point contacts, Phys. Rev. Lett. 92, 027201 (2004).