In search of a model for dilute magnetic semiconductors

 

Dr. Priya Mahadevan (S.N Bose Center for Basic Sciences, Kolkata)

 

Abstract: While there has been a flurry of activity in the study of dilute magnetic semiconductors, there is no consensus about the mechanism of magnetism. We have considered various limiting situations and examined the results obtained from first principle calculations on a host of materials in an attempt to construct a picture of the microscopics. While the most popular view is that of an isolated transition metal spin interacting with a sea of electrons in the conduction band via an RKKY-type mechanism, we show that in this limit, ferromagnetism is strongly reduced and becomes short-ranged. Surprisingly, the limit of a hole occupying an impurity band split off from the host valence band shows strong stability of the ferromagnetic state.