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Electron cotunneling through doubly occupied quantum dots: effect of spin configuration.

Lan J, Sheng W - Nanoscale Res Lett (2011)

Bottom Line: A microscopic theory is presented for electron cotunneling through doubly occupied quantum dots in the Coulomb blockade regime.Beyond the semiclassic framework of phenomenological models, a fully quantum mechanical solution for cotunneling of electrons through a one-dimensional quantum dot is obtained using a quantum transmitting boundary method without any fitting parameters.Furthermore, it is found that the cotunneling conductance reveals more sensitive dependence on the barrier width than the height.

View Article: PubMed Central - HTML - PubMed

Affiliation: Department of Physics, Furan University, Shanghai 200433, PR China. shengw@fudan.edu.cn.

ABSTRACT
A microscopic theory is presented for electron cotunneling through doubly occupied quantum dots in the Coulomb blockade regime. Beyond the semiclassic framework of phenomenological models, a fully quantum mechanical solution for cotunneling of electrons through a one-dimensional quantum dot is obtained using a quantum transmitting boundary method without any fitting parameters. It is revealed that the cotunneling conductance exhibits strong dependence on the spin configuration of the electrons confined inside the dot. Especially for the triplet configuration, the conductance shows an obvious deviation from the well-known quadratic dependence on the applied bias voltage. Furthermore, it is found that the cotunneling conductance reveals more sensitive dependence on the barrier width than the height.

No MeSH data available.


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Differential conductance for an electron transporting through a doubly occupied quantum dot calculated as a function of the applied bias voltage. Inset: a schematic view of the model system.
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Figure 1: Differential conductance for an electron transporting through a doubly occupied quantum dot calculated as a function of the applied bias voltage. Inset: a schematic view of the model system.

Mentions: An approach beyond the conventional phenomenological models is presented to directly solve the many-body Hamiltonian in the electron transport through a few-electron system without applying any approximations to the electron-electron interaction. A schematic view of our model system is shown in the inset of Figure 1. The quantum dot is modeled as a one-dimensional double-barrier structure, each barrier has a height of 50.0 meV and width of 5.0 nm, and the potential well in-between has a width of 30.0 nm and depth of -15.0 meV below the bottom of the outside barriers. Considering the penetration of the confined states into the barriers, we have placed two buffer layers on the left and right sides of the system.


Electron cotunneling through doubly occupied quantum dots: effect of spin configuration.

Lan J, Sheng W - Nanoscale Res Lett (2011)

Differential conductance for an electron transporting through a doubly occupied quantum dot calculated as a function of the applied bias voltage. Inset: a schematic view of the model system.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC3211313&req=5

Figure 1: Differential conductance for an electron transporting through a doubly occupied quantum dot calculated as a function of the applied bias voltage. Inset: a schematic view of the model system.
Mentions: An approach beyond the conventional phenomenological models is presented to directly solve the many-body Hamiltonian in the electron transport through a few-electron system without applying any approximations to the electron-electron interaction. A schematic view of our model system is shown in the inset of Figure 1. The quantum dot is modeled as a one-dimensional double-barrier structure, each barrier has a height of 50.0 meV and width of 5.0 nm, and the potential well in-between has a width of 30.0 nm and depth of -15.0 meV below the bottom of the outside barriers. Considering the penetration of the confined states into the barriers, we have placed two buffer layers on the left and right sides of the system.

Bottom Line: A microscopic theory is presented for electron cotunneling through doubly occupied quantum dots in the Coulomb blockade regime.Beyond the semiclassic framework of phenomenological models, a fully quantum mechanical solution for cotunneling of electrons through a one-dimensional quantum dot is obtained using a quantum transmitting boundary method without any fitting parameters.Furthermore, it is found that the cotunneling conductance reveals more sensitive dependence on the barrier width than the height.

View Article: PubMed Central - HTML - PubMed

Affiliation: Department of Physics, Furan University, Shanghai 200433, PR China. shengw@fudan.edu.cn.

ABSTRACT
A microscopic theory is presented for electron cotunneling through doubly occupied quantum dots in the Coulomb blockade regime. Beyond the semiclassic framework of phenomenological models, a fully quantum mechanical solution for cotunneling of electrons through a one-dimensional quantum dot is obtained using a quantum transmitting boundary method without any fitting parameters. It is revealed that the cotunneling conductance exhibits strong dependence on the spin configuration of the electrons confined inside the dot. Especially for the triplet configuration, the conductance shows an obvious deviation from the well-known quadratic dependence on the applied bias voltage. Furthermore, it is found that the cotunneling conductance reveals more sensitive dependence on the barrier width than the height.

No MeSH data available.


Related in: MedlinePlus