Making Semiconductors Ferromagnetic: Reasons, Challenges, and Opportunities

December 1, 2006
Jacek Furdyna | Department of Physics, University of Notre Dame

It has recently been discovered that incorporating Mn into the lattice of a III-V semiconductor (such as GaAs) will render the semiconductor ferromagnetic. The ferromagnetism of these alloys occurs because Mn ions, in addition to bringing magnetic moments into the III-V host, also act as acceptors, thus providing large concentrations of holes. The Curie temperatures (which are determined by both the Mn and the free carrier concentration) currently reach about 190 K. Major efforts are being made around the world to increase this value because of the possible applications of III1-xMnxV alloys in spin electronics (“spintronics”), where the vision is to harness the spin degree of freedom of the electron – in addition to its charge – in order to achieve new multi-functional spin-electronic devices. But for such devices to be of practical importance, they must operate at room temperature. I will discuss the fundamental magnetic properties of these new ferromagnetic semiconductor materials; the mechanisms which presently limit their Curie temperatures; various strategies to overcome this obstacle in order to achieve semiconductors that are ferromagnetic above room temperature; and I will describe examples of device prototypes based on III1-xMnxV alloys which have already been demonstrated, and which hold promise of spintronic applications once room-temperature ferromagnetism is achieved in these materials.

NOTE: As a part of Polish Speaker Distinguished Lecture Series, Prof. Furdyna will talk about “How the Means Become the End in Scientific Discovery: the Impact of Unintended Consequences” at University of Washington, Kane Hall, 7pm on December 1, 2006.

Speaker Details

JACEK FURDYNA currently holds the Marquez Endowed Chair in Information Theory and Computer Technology at the University of Notre Dame. He obtained his Ph.D. degree in experimental solid state physics at Northwestern University in 1960. After a period of additional postdoctoral research at Northwestern and M.I.T. he joined the Physics Faculty of Purdue University in 1966, where he remained until 1987. During the years 1982 to 1985 he served as Director of the Materials Research Laboratory, a major multi-disciplinary program sponsored by the National Science Foundation focused on research in leading issues of materials science. In 1987 he was appointed to the Marquez Endowed Chair of Information Theory and Computer Technology at the University of Notre Dame. During his career his research interests included spectroscopy of solids; fabrication and investigation of man-made