With the help of a recent federal grant, a physics research team is working to develop new magnetic materials that could lead to such applications as electric airplanes, unmanned underwater vehicles and quieter and more efficient electric motors.

The team, led by George C. Hadjipanayis, Richard B. Murray Professor of Physics, has been awarded a $4.27 million grant by the Defense Sciences Office of the federal Defense Advanced Research Projects Agency (DARPA) to develop novel magnetic meta materials.

Meta materials are artificially constructed materials that exhibit responses not found in nature. The research team is working to develop new classes of meta materials with previously unattainable, low-frequency magnetic properties and to integrate those materials into device prototypes that will enable new and enhanced capabilities for the military and for industry with great energy savings.

The research will involve both permanent magnets and soft magnetic materials. In permanent magnets, research will focus on nanocomposite magnets, consisting of a fine mixture of magnetically hard and soft phases with a grain size of about 10-20 nanometers. For a sense of scale, one nanometer equals one one-thousandth of a micron, and one micron equals one one-thousandth of a millimeter.

In soft magnets, research will focus on fiber-reinforced cobalt-iron alloys with negligible creep at high temperatures and on artificially made ferrites.

The new hard and soft magnets to be discovered will allow the development of more electric airplanes for the U.S. Air Force and also of unmanned underwater vehicles and torpedoes, Hadjipanayis says. Additionally, he says, high performance permanent magnets could enable electric drives for tanks and automobiles, quieter and more efficient electric motors and bearings for lubrication-free motors and generators.

Meta materials also offer promising opportunities for future applications, including new solutions to antenna proliferation and radio frequency interference, open magnetic resonance imaging (MRI), faster spindle motors for computer hard drives and wireless power transfer.

In addition to Hadjipanayis, the UD team includes Karl M. Unruh and John Q. Xiao, both physics department faculty members, and Siu-Tat Chui of the College's Bartol Research Institute. Also included are scientists from Carnegie Mellon University, the Naval Research Laboratory, NanoPac Inc., Electron Energy Corp., Materials Modifications Inc. and Advanced Ceramic Research.

According to Valerie Browning, who directs the DARPA meta materials program, the physics of conventional bulk materials and the design constraints associated with them limit their ultimate performance. Due to a new "small-scale" physics associated with their engineering, meta materials exhibit superior properties and enhanced performance, she says.

The "small-scale" physics occurs when the size of the composite becomes of the same order as the characteristic length of the physical property. For magnets, this is the domain wall thickness.

The aim of meta materials development is to engineer unit cell building blocks that have dimensions commensurate with small-scale physics and to assemble these building blocks into three-dimensional, large-scale bulk materials while still preserving their unique and superior properties, Hadjipanayis says.

The goal of the four-year UD program is to develop and demonstrate novel meta materials by controlling and manipulating the material properties at the nanoscale. The new magnetic materials to be developed will afford new and enhanced capabilities for a number of crucial military applications.

--Neil Thomas, AS '76