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Efficient spin filter using multi-terminal quantum dot with spin-orbit interaction.

Yokoyama T, Eto M - Nanoscale Res Lett (2011)

Bottom Line: First, we formulate the spin Hall effect (SHE) in a quantum dot connected to three leads.We show that the SHE is significantly enhanced by the resonant tunneling if the level spacing in the quantum dot is smaller than the level broadening.We stress that the SHE is tunable by changing the tunnel coupling to the third lead.

View Article: PubMed Central - HTML - PubMed

Affiliation: Faculty of Science and Technology, Keio University, 3-14-1 Hiyoshi, Kohoku-ku, Yokohama 223-8522, Japan. tyokoyam@rk.phys.keio.ac.jp.

ABSTRACT
We propose a multi-terminal spin filter using a quantum dot with spin-orbit interaction. First, we formulate the spin Hall effect (SHE) in a quantum dot connected to three leads. We show that the SHE is significantly enhanced by the resonant tunneling if the level spacing in the quantum dot is smaller than the level broadening. We stress that the SHE is tunable by changing the tunnel coupling to the third lead. Next, we perform a numerical simulation for a multi-terminal spin filter using a quantum dot fabricated on semiconductor heterostructures. The spin filter shows an efficiency of more than 50% when the conditions for the enhanced SHE are satisfied.PACS numbers: 72.25.Dc,71.70.Ej,73.63.Kv,85.75.-d.

No MeSH data available.


Related in: MedlinePlus

Models of a multi-terminal spin filter using a quantum dot with SO interaction. (a) Impurity Anderson model with three leads. There are two energy levels (j = 1, 2) in the quantum dot. They are connected to lead by tunnel coupling, Vα,j (b) A three-terminal spin-filtering device fabricated on semiconductor heterostructures. 2DEG is confined in the xy plane. A quantum dot is formed by quantum point contacts on three leads. Reservoir S is a source from which spin-unpolarized electrons are injected into the quantum dot. The voltage is identical in reservoirs D1 and D2.
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Figure 1: Models of a multi-terminal spin filter using a quantum dot with SO interaction. (a) Impurity Anderson model with three leads. There are two energy levels (j = 1, 2) in the quantum dot. They are connected to lead by tunnel coupling, Vα,j (b) A three-terminal spin-filtering device fabricated on semiconductor heterostructures. 2DEG is confined in the xy plane. A quantum dot is formed by quantum point contacts on three leads. Reservoir S is a source from which spin-unpolarized electrons are injected into the quantum dot. The voltage is identical in reservoirs D1 and D2.

Mentions: In the present article, we investigate an enhancement of the SHE by the resonant tunneling through a quantum dot (QD) with strong SO interaction, e.g., InAs QD [29-34]. The QD shows a peak structure of the current as a function of gate voltage, the so-called Coulomb oscillation. At the current peaks, the resonant tunneling takes place at low temperatures. First, we consider an impurity Anderson model with three leads, as shown in Figure 1a. There are two energy levels in the QD. We show a remarkable enhancement of the SHE when the level spacing in the QD is smaller than the level broadening. The SHE is electrically tunable by changing the tunnel coupling to the third lead.


Efficient spin filter using multi-terminal quantum dot with spin-orbit interaction.

Yokoyama T, Eto M - Nanoscale Res Lett (2011)

Models of a multi-terminal spin filter using a quantum dot with SO interaction. (a) Impurity Anderson model with three leads. There are two energy levels (j = 1, 2) in the quantum dot. They are connected to lead by tunnel coupling, Vα,j (b) A three-terminal spin-filtering device fabricated on semiconductor heterostructures. 2DEG is confined in the xy plane. A quantum dot is formed by quantum point contacts on three leads. Reservoir S is a source from which spin-unpolarized electrons are injected into the quantum dot. The voltage is identical in reservoirs D1 and D2.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC3211854&req=5

Figure 1: Models of a multi-terminal spin filter using a quantum dot with SO interaction. (a) Impurity Anderson model with three leads. There are two energy levels (j = 1, 2) in the quantum dot. They are connected to lead by tunnel coupling, Vα,j (b) A three-terminal spin-filtering device fabricated on semiconductor heterostructures. 2DEG is confined in the xy plane. A quantum dot is formed by quantum point contacts on three leads. Reservoir S is a source from which spin-unpolarized electrons are injected into the quantum dot. The voltage is identical in reservoirs D1 and D2.
Mentions: In the present article, we investigate an enhancement of the SHE by the resonant tunneling through a quantum dot (QD) with strong SO interaction, e.g., InAs QD [29-34]. The QD shows a peak structure of the current as a function of gate voltage, the so-called Coulomb oscillation. At the current peaks, the resonant tunneling takes place at low temperatures. First, we consider an impurity Anderson model with three leads, as shown in Figure 1a. There are two energy levels in the QD. We show a remarkable enhancement of the SHE when the level spacing in the QD is smaller than the level broadening. The SHE is electrically tunable by changing the tunnel coupling to the third lead.

Bottom Line: First, we formulate the spin Hall effect (SHE) in a quantum dot connected to three leads.We show that the SHE is significantly enhanced by the resonant tunneling if the level spacing in the quantum dot is smaller than the level broadening.We stress that the SHE is tunable by changing the tunnel coupling to the third lead.

View Article: PubMed Central - HTML - PubMed

Affiliation: Faculty of Science and Technology, Keio University, 3-14-1 Hiyoshi, Kohoku-ku, Yokohama 223-8522, Japan. tyokoyam@rk.phys.keio.ac.jp.

ABSTRACT
We propose a multi-terminal spin filter using a quantum dot with spin-orbit interaction. First, we formulate the spin Hall effect (SHE) in a quantum dot connected to three leads. We show that the SHE is significantly enhanced by the resonant tunneling if the level spacing in the quantum dot is smaller than the level broadening. We stress that the SHE is tunable by changing the tunnel coupling to the third lead. Next, we perform a numerical simulation for a multi-terminal spin filter using a quantum dot fabricated on semiconductor heterostructures. The spin filter shows an efficiency of more than 50% when the conditions for the enhanced SHE are satisfied.PACS numbers: 72.25.Dc,71.70.Ej,73.63.Kv,85.75.-d.

No MeSH data available.


Related in: MedlinePlus