The next Physics Cafe will be tomorrow (March 15) at 2:30 p.m. in Horan-O’Donnell Room 015. James Pientka ’07 will present a talk about his research with quantum dots. Pientka is currently a PhD candidate at the University at Buffalo.
Abstract:
Quantum Dots are semiconductors with unique electronic properties closely related to the size of the individual crystals that make up the material. They have been studied in transistors, solar cells, LEDs, and diode lasers. We study semiconductor Quantum Dots (QDs) with magnetic impurities. The magnetism in these systems can be controlled in ways not possible in bulk semiconductors [1]. Robust magnetic effects have been observed recently in both colloidal and self-assembled QDs [2,3]. Here, we develop a rate-equations approach to describe the carrier-mediated magnetic ordering in QDs. In this situation, the magnetic properties are different from the steady-state scenario, due to different carrier spin density, which affects the magnetic-impurity alignment. We focus on a type-II QD band profile, where the electrons reside in the barrier, while the holes are localized in the QD interior, which contains the magnetic impurities.
Supported by Department Of Energy – Office of Basic Energy Sciences (DOE-BES), U.S. Office of Naval Research (US ONR), Air Force Office of Scientific Research (AFOSR), National Science Foundation Division of Materials Research (NSF-DMR), and the National Science Foundation Electrical, Communications and Cyber Systems Faculty Early Career Development (NSF-ECCS CAREER) program.
(1) R. M. Abolfath, A. G. Petukhov, and I. Zutic, Phys. Rev. Lett. 101, 207202 (2008); I. Zutic and A. G. Petukhov, Nature Mater.4, 623 (2009).
(2) R. Beaulac et al., Science 325, 973 (2009).
(3) I. R. Sellers, R. Oszwaldowski, et al., Phys. Rev. B 82, 195320 (2010).
Submitted by: Michael Wood, PhD, assistant professor, physics
