Abstract : The dilute magnetic semiconductors are an emerging area of interest because of their possible applications in spintronics. In this talk, the phenomenon and the current status of ferromagnetism in the dilute magnetic semiconductors such as GaAs(Mn) and GaN(Mn) will be discussed. Two ways to control the ferromagnetism in these materials will be examined. One is by increasing the carrier concentration by putting the magnetic atoms at the interface between two wurtzite semiconductors, where a two-dimensional hole gas (2DHG) forms because of the spontaneous polarization difference between the two crystals. The increased carrier concentration strengthens the ferromagnetic interaction between the Mn moments. And the second is by shining light on the sample. In this “photomagnetic effect”, the incident light creates extra carriers (electrons and holes) across the band gap, thereby enhancing the carrier-mediated ferromagnetism between the localized Mn moments. The effect will be illustrated by examining a model Hamiltonian that includes the kinetic energy and the Coulomb interaction terms and the coupling of the carriers to light. The Hamiltonian is solved by a Bogoliubov transformation and then by minimizing the ground-state energy by a variational method. The theoretical results will be compared with the appropriate experimental data, where available.

The seminar will be held at 3:30pm in 138 SES . UIC Physics Dept/SES. is located at 845 W Taylor St., Chicago, IL, 60607