New Technique Allows 3-D Mapping of the Magnetic Vector Potential
Amanda Petford-Long [Photo courtesy: Argonne National Laboratory]
Scientists at the U.S. Department of Energy’s (DOE) Argonne National Laboratory have developed a new technique  that maps the magnetic vector potential — one of the most important electromagnetic quantities and a foundation of quantum mechanics — in three dimensions. The vector potential is central to a number of areas of condensed matter physics, such as superconductivity and magnetism.
"The vector potential of magnetic structures is essential to the understanding of several areas in condensed matter physics and magnetism on a quantum level, but until now it has never been visualized in three dimensions,” Argonne Distinguished Fellow Amanda Petford-Long said. “If you want to understand the way magnetic nanostructures behave, then you have to understand the magnetic vector potential.”
According to Petford-Long, research into the creation and manipulation of magnetic nanostructures will enable the development of the next generation of data storage in the form of magnetic random access memory.
Charudatta Phatak [Photo Courtesy: Argonne National Laboratory]
Petford-Long and post-doctoral researcher Charudatta Phatak used a transmission electron microscope (TEM) to examine a series of different nanostructures. The theoretical and numerical reconstruction procedure was developed in collaboration with Prof. Marc De Graef at Carnegie Mellon University.
Using the TEM, the researchers were able to take images from several different angles and then rotate the structure by 90 degrees until they had several series of images. The scientists then extracted the vector potential by reconstructing how the electrons in the material shifted phase.
“The development of next generation magnetic sensors and devices requires studying the physics underlying the magnetic interactions at the nanoscale,” Phatak said. “This 3-D map is the first step to truly understanding those interactions.”
Marc De Graef [Photo courtesy: Carnegie Mellon University]
Funding for the research, including the TEM situated in the Materials Science Division, was provided by the U.S. Department of Energy’s Office of Science. The patterned structures were prepared at the Center for Nanoscale Materials with Alexandra Imre.
The Center for Nanoscale Materials at Argonne National Laboratory is one of the five DOE Nanoscale Science Research Centers (NSRCs), premier national user facilities for interdisciplinary research at the nanoscale, supported by the DOE Office of Science. For more information about the DOE NSRCs, visit http://nano.energy.gov/.
 Charudatta Phatak, Amanda K. Petford-Long, Marc De Graef, "Three-Dimensional Study of the Vector Potential of Magnetic Structures", Phys. Rev. Lett. 104, 253901 (2010). Abstract.
[We thank Argonne National Laboratory for materials used in this posting]