Simulation of Single -Electron Charging Effects in Planar Nanoscale Devices

By expanding the model to incorporate electron spin under the Local Spin Density Approximation, the charging properties of the double quantum dot are investigated in terms of electron spin and interdot interaction. It is shown that both electrostatic and quantum mechanical coupling between the dots affect the charging properties. For weak interdot coupling, simultaneous or double charging of the two constituent dots occurs, as seen in recent experiments by Waugh and co-workers [2]. It is argued that the double charging model may be used to explain the phenomenon of pair tunneling in vertical dots observed by Ashoori et al. [3]. It is also shown that a spin polarized state can be realized for weak interdot coupling, with four electrons in each dot, a situation explained in terms of Hund's rules. Lastly, it is shown that a ferromagnetic-like state can be obtained for three electrons in the double-dot by varying the interdot coupling strength. As the interdot barrier is lowered, the pz states in the two dots couple to form a bonding state that is delocalized over both. For small energy spacing between the 1 s and the bonding states, the ground state for three electrons has an electron in the 1s state of each dot and the delocalized pz bonding state, with the spins of all the electrons aligned parallel.

Name thesis:degree_name

Ph.D.

Level thesis:degree_level

Dissertation

Discipline thesis:degree_discipline

Electrical Engineering

Grantor

University of Illinois at Urbana-Champaign

Year dc:date

2015

Author dc:creator

• Nagaraja, Satyadev Hulikal

Contributors dc:contributor

• Leburton, Jean-Pierre

• Physics, Condensed Matter

Language dc:language

eng

Identifier

(MiAaPQ)AAI9953098

OAI identifier oai:identifier

oai:www.ideals.illinois.edu:2142/81311