Past Seminars

The weekly seminar series organized by CNT and the Molecular Engineering and Sciences Institute provides a forum for bringing national and international leaders in nanoscale science and technology to campus, and for graduate students enrolled in our Dual Ph.D. program in Nanotechnology to present their research.

All seminars are held on Tuesdays from 2:30 to 3:20 PM in Johnson Hall Room 102 (North end of building and across from MolE).

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Seminars

2013-02-19

Unconventional Magnetic Ordering in Quantum Dots

Assoc. Prof. Igor Zutic , University at Buffalo - Dept. of Physics
Speaker's Website
Xiaosong Li, Dept. of Chemistry

The formation of a magnetic polaron (MP) can be viewed as a cloud of localized magnetic ion spins, aligned through an exchange interaction with a confined carrier spin and is typically considered a low-temperature phenomenon in semiconductors. However, recent experimental advances in colloidal nanocrystals and epitaxially grown quantum dots show robust signatures of MPs that can persist up to room temperature and lead to effective internal fields up to 100 tesla [1]. These highly tunable semiconductor nanostructures, allowing versatile control of the number of carriers, their spin, and the effects of quantum confinement, offer intriguing possibilities for magnetism. We suggest how magnetic ordering can be controlled even at a fixed number of carriers [2], enhanced by heating [3], and present in closed-shell systems [4]. We expect that doping quantum dots with magnetic impurities may open unexplored opportunities to study the nanoscale correlations [5]. Through Mn-carrier exchange interaction, molecular-like correlations can be enhanced, imprinted on Mn spins, and thus observed. We propose experiments to verify our predictions.