6 March 2000
Investigators: W. F. Egelhoff, Jr., P .J. Chen (Guest Researcher), D. Parks (Guest Researcher),G. Serpa (Guest Researcher), D. Barak (Guest Researcher), and W. W. Miller (Guest Researcher)
Objectives:
The objective of this program is to provide assistance to U.S. companies manufacturing products based on giant magnetoresistance (GMR) materials. These materials are used primarily in the computer hard-disk drive industry, but emerging markets include nonvolatile memory chips, magnetic field sensors, and ultrahigh speed isolators. We help these companies learn how to produce improved GMR materials so that they can operate successfully in the increasingly competitive world market. Our work provides U.S. companies with significant competitive help by investigating the science underlying the manufacturing process, something these companies cannot adequately do on their own.
Technical Description:
Within a few years we will all be surrounded in our daily lives by consumer products that make use of GMR materials. As a result, GMR materials have become a matter of great economic importance. Not unexpectedly, a worldwide race is underway to develop the best GMR materials. A list of companies which have GMR-materials development programs underway is provided below:
U.S. Japan Europe
IBM Toshiba Philips Hewlett-Packard Hitachi Siemens Motorola Sony Thompson-CS Honeywell NEC Boesch Read-Rite Sanyo Nonvolatile Electronics Alps Quantum Toyota Applied Magnetics Fujitsu Ford Nisshin Steel CDC Vacuum TDK Seagate Matsushita Veeco Mitsubishi Shimadzu
Computer memory and hard-disk-drive products are a major force in today's economy, representing over $50 billion in annual sales, worldwide. The U.S. has a strong, but precarious, position in hard-disk-drives and is trying to make a comeback memory products, but intense competition from overseas industries, especially Japan, has put the U.S. future at risk in these areas. Competition is forcing U.S. companies to rush GMR materials into products and onto the market. This rush-to-market comes at the expense of scientific research on how to improve GMR materials. Japanese companies, however, do not follow this pattern, and most of the long-range research in GMR materials is presently being done in Japan. This situation puts the current U.S. lead in GMR products in jeopardy.
There are many applications for GMR materials beyond just computer products. GMR-based magnetic sensors, which can detect the presence and motion of magnets and other iron-containing objects, are better than existing sensors and have a host of applications. These include automation of factory production lines with position-sensing robots, antilock breaking systems for cars, "smart" shock absorbers, vehicle-counting systems, currency sorting and counting based on magnetic inks, and on and on.
To assist U.S. industry, NIST set up a major new research program specifically aimed at providing the scientific understanding and measurement capability needed to allow U.S. industry to fabricate the best GMR materials in the world. This program was centered on a new facility, known as the Magnetic Engineering Research Facility (MERF), which is the most elaborately instrumented magnetic thin-film production facility ever constructed. No comparable facility exists even in the R&D labs of major companies such as IBM and Sony.
This unique facility puts NIST in an excellent position to assist not only the small companies in the GMR market but even the major ones. Over the past few years NIST researchers have developed the measurement techniques, clarified the scientific issues, and established the manufacturing processes needed to produce the highest quality GMR materials. NIST is presently capable of producing, albeit on a small scale, the best GMR materials in the world.
Planned Outcome:
Our work is anticipated to help U.S. companies overcome Japan's advantage in GMR research and remain the world leader in this field of GMR materials. U.S. companies are eagerly working with us to transfer the improved manufacturing processes that we have developed into their production facilities.
The Department of Defense is also very interested in GMR materials (again for a wide range of applications) and our work has been supported for the past three years by a grant from the Defense Advanced Projects Research Agency (DARPA).
External Collaborations:
We have collaborated with a number of industries in the area of GMR materials, including Motorola, IBM, Nonvolatile Electronics, Honeywell, Commonwealth Scientific, and Veeco. We have also collaborated with a number of university groups, including those of Prof. Charlie Falco, U. of Arizona, Prof. Mel Gomez, U. of Maryland, Prof. Ami Berkowitz, U. of California, San Diego, Prof. Karen Kavanvagh, U. of California, San Diego, Prof. Dave Smith, Arizona State, and Prof. Jack Judy, U. of Minnesota, and with scientists from two national labs, George Sandos of NRL and Bill Butler of Oak Ridge. In all cases we have been making samples for these collaborators for them to analyze in their facilities or we have been examining their samples in our facilities.
Accomplishments:
The Magnetic Engineering Research Facility (MERF) at NIST, the most elaborately instrumented thin-film deposition facility in the world, was maintained at an operational status of approximately 95 % of available time, meaning the facility was down only 5% of the time.
This year we continued to investigate a promising variant of GMR materials in which Al2O3 is used in place of Cu as the spacer between magnetic layers. These promising new materials are known as magnetic tunnel junctions (MJTs) and are particularly well suited to being the memory element in nonvolatile computer memory chips. In studying MJTs we observed Al diffusing into the underlying magnetic metal and found that oxidation of the magnetic layer, prior to Al-deposition, can suppress this undesirable effect. We are currently working with U.S. industry to find ways to make use of this discovery in a production environment.
One of the important accomplishments of FY1999 was our work with Commonwealth Scientific. A GMR thin-film deposition system that Commonwealth had built for Honeywell did not meet acceptance criteria. After we identified the problem, Commonwealth was able to correct it. Due to our work, the system is now up and running at Honeywell and will help keep the U.S. in the lead in the international race to commercialize GMR-based random access memory chips.
Impacts:
The new information produced in this work is being transferred to U.S. companies in the magnetic data-storage industry through visits by NIST staff to those companies and by frequent telephone and e-mail contacts. Our key collaborators are Motorola, IBM, Seagate, Nonvolatile Electronics, and Read-Rite. These collaborators are attempting to implement our findings in their production equipment. This advanced knowledge together with our supporting consultations is giving U.S. companies a head start in developing the next generation of production facilities.
Output:
Publications:
Egelhoff, Jr., W. F., Chen, P. J., Powell, C. J., Parks, D., McMichael, R. D., Judy, J. H., Martien, D., Berkowitz, A. E., and Daughton, J. M., "Optimizing GMR Spin Valves: The Outlook for Improved Properties," Proc. 1998 International Nonvolatile Memory Technology Conference, IEEE Publications, Piscataway, NJ, page 34, 1998.
Fry, R. A., Bennett, L. H., Della Torre, E., Shull, R. D., Egelhoff, Jr., W. F., Farrow, R. F. C., and Lee, C. H., "Magneto-Optical Measurements of Ultrathin Co-Pt(111) Multilayers," J. Mag. Mag. Mat. 193, 162, 1999.
Egelhoff, Jr., W. F., Chen, P. J., Powell, C. J., Parks, D., McMichael, R. D., Judy, J. H., Martien, D., Berkowitz, A. E., and Daughton, J. M., "Surface Effects in the Growth of GMR Spin Valves," MRS Symp. Proc. 517, 289, 1999.
McMichael, R. D., Stiles, M. D., Chen, P. J., and Egelhoff, Jr., W. F., "Ferromagnetic Resonance Studies of NiO-Coupled Thin Films of Ni80Fe20," Phys. Rev. B. 58, 8605, 1998.
Egelhoff, Jr., W. F., Chen, P. J., Powell, C. J., Parks, D., Serpa, G., McMichael, R. D., Martien, D., and Berkowitz, A. E., "Specular Electron Scattering in Metallic Thin Films," Proc. 26th Conf. on the Physics and Chemistry of Semiconductor Interfaces, J. Vac. Sci. Technol. B 17, 1702, 1999.
Chopra, H. D., Yang, D. X., Chen, P. J., Brown, H. J., Swartzendruber, L. J., and Egelhoff, Jr., W. F., "Nature of Magnetization Reversal in Exchange Coupled NiO-Co bilayers," accepted by Physical Review B.
Yang, D. X., Chopra, H. D., Chen, P. J., Brown, H. J., Swartzendruber, L. J., and Egelhoff, Jr., W. F., "Modification of Magnetic Properties in Giant Magnetoresistive Spin Valves Using Pb as a Surface Modifying Species," accepted by J. Appl. Phys.
Chopra, H. D., Yang, D. X., Chen, P. J., Brown, H. J., Swartzendruber, L. J., and Egelhoff, Jr., W. F., "Magnetization Reversal in Polycrystalline Exchange Coupled NiO-Co bilayers," accepted by J. Appl. Phys.
Bae, S., Judy, J. H., Egelhoff, Jr., W. F., and Chen, P. J., "The Dependence of Exchange Coupling on the Surface Roughness and Structure in -Fe2O3 and NiFe/ - Fe2O3 Bi-layers," accepted by J. Appl. Phys.
Bae, S., Judy, J. H., Egelhoff, Jr., W. F., and Chen, P. J., "Bottom GMR Spin Valves Using a RF Reactive Bias Sputtered - Fe2O3 Antiferromagnetic Layer," accepted by J. Appl. Phys.
Lu, R. P., Morgan, B. A., Kavanagh, K. L., Powell, C. J., Chen, P. J., Serpa, G., and Egelhoff, Jr., W. F., "Hot Electron Attenuation Lengths in Ultrathin Magnetic Films," accepted by J. Vac. Sci. Technol.
Presentations:
W. F. Egelhoff, Jr., "Surface Effects in the Growth of GMR Spin Valves," Physics Dept., Invited Talk, Montana State Univ., October 1998.
W. F. Egelhoff, Jr., "Recent Studies of the GMR Effect at NIST," Motorola/DARPA Workshop, Invited Talk, Miami, FL, November 1998.
W. F. Egelhoff, Jr., "Surface and Interface Effects in the Growth of GMR Spin Valves," MSEL Invited Lunch Talk, Gaithersburg, MD, December 1998.
W. F. Egelhoff, Jr., "Specular Electron Scattering in Metallic Thin Films," (poster) 26th Conf. on the Physics and Chemistry of Semiconductor Interfaces, Invited Talk, San Diego, CA, January 1999.
W. F. Egelhoff, Jr., "Surface and Interface Effects in the Growth of GMR Spin Valves," 26th Conf. on the Physics and Chemistry of Semiconductor Interfaces, Invited Talk, San Diego, CA, January 1999.
W. F. Egelhoff, Jr., "Surface and Interface Effects in the Growth of GMR Spin Valves," Invited Talk, Physics Dept., U.C. San Diego, CA, February 1999.
W. F. Egelhoff, Jr., "Optimizing GMR Spin Valves: The Outlook for Improved Properties," Read Rite Corp., Invited Talk, Fremont, CA, April 1999.
W. F. Egelhoff, Jr., "Interdiffusion in the Growth of Al on Magnetic Metals," Nonvolatile Electronics, Invited Talk, Eden Prairie, MN, May 1999.
W. F. Egelhoff, Jr., "Interdiffusion in the Growth of Al on Magnetic Metals," Seagate Research Labs, Invited Talk, Minneapolis, MN, May 1999.
W. F. Egelhoff, Jr., "Interdiffusion in the Growth of Al on Magnetic Metals," (invited poster), DARPA Spintronics Workshop, Invited Talk, White Plains, NY, July 1999.
W. F. Egelhoff, Jr., "New Materials for Ultrahigh density Digital Data Storage," ATP Intramural Project Review, NIST, Invited Talk, August 26, 1999.
6 March 2000