TITLE: Diluted magnetic semiconductors based the layered A₂^VB₃^VI compounds

SPEAKER: Dr. Jeffrey S. Dyck,

TIME: Thursday Jan. 30, 2003 at 4 PM

PLACE: George P. Williams, Jr. Lecture Hall, (Olin 101)

Currently, there is a great deal research activity on the incorporation of magnetic ions into semiconductors to produce ferromagnetism. These diluted magnetic semiconductors (DMSs) are of interest both to theorists, because of their unusual mechanisms of magnetic behavior, and to experimentalists, because the manipulation of spin in addition to charge promises devices based on spin polarized transport. The most extensively studied DMS systems to date are based on II-VI and III-V semiconductors doped with manganese. Recently, we discovered a new class of diluted magnetic semiconductors that differ from the traditional compounds a number of intriguing ways. The narrow band gap tetradymite-type semiconductors with the form A₂^VB₃^VI (A = Sb, Bi and B = Se, Te) are normally associated with thermoelectric cooling devices. However, both Sb_2-xV_xTe₃ and Bi_2-xFe_xTe₃ display ferromagnetic semiconductor behavior. In this talk, I will discuss the interesting properties of these compounds as well the doping of other 3d transition metals in the tetradymite structure semiconductors.