Condensed Matter Seminar Series

Electron Transport in Correlated Nanostructures

Khaled A. Al-Hassanieh

University of Tennessee, Oak Ridge National Laboratory, and Florida State University

Monday February 26,  10:45 am,  Room 246 (HEP conference room)  

Abstract:  There has been a rapidly increasing interest in studying systems on the nanometer scale in the past decade.  The importance of such systems cannot be overstated both from the basic research and applied points of view.  Due to their small sizes and confined nature, the electronic correlations are dominant.  This has been manifested in the observation of several effects such as the Kondo effect in quantum dots (QDs), molecular transistors, and other nanosystems.  I will first present a brief overview of correlation effects in nanosystems.  Then I will discuss the results of some of our recent numerical simulations.  In the first study [1], we investigated the transport properties of coupled double-level QDs.  We observed the formation of a novel ferromagnetic phase in the quarter filling regime.  This phase represents a QD realization of the double exchange mechanism.  In a second study [2], we reproduced numerically the results of an important experiment involving two QDs coupled through an open region [3].  The experimental results indicate the mesoscopic realization of RKKY interaction.  Our results, on the other hand indicate the possibility of Fano antiresonance.  Finally, I will introduce a new procedure to study nanotransport using the recently developed adaptive time-dependent density-matrix renormalization group [4].

[1]  G. B. Martins et al., Phys. Rev. Lett. 94, 026804 (2005).
[2]  G. B. Martins et al., Phys. Rev. Lett. 96, 066802 (2006).
[3]  N. J. Craig et al., Science 304, 565 (2004).
[4]  K. A. Al-Hassanieh et al., Phys. Rev. B 73, 195304 (2006).