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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

Results of the numerical simulation for the spin-filtering device shown in Fig. 1(b). The conductance G± for spin sz = ±1/2 from reservoir S to D1 is shown as a function of gate voltage Vg on the quantum dot. Solid and broken lines indicate G+ and G-, respectively. The height of the tunnel barriers is US = UD1 = UD2 = 0.9EF.
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Figure 3: Results of the numerical simulation for the spin-filtering device shown in Fig. 1(b). The conductance G± for spin sz = ±1/2 from reservoir S to D1 is shown as a function of gate voltage Vg on the quantum dot. Solid and broken lines indicate G+ and G-, respectively. The height of the tunnel barriers is US = UD1 = UD2 = 0.9EF.

Mentions: Figure 3 presents the conductance G± for spin sz = ±1/2 as a function of the gate voltage Vg on the QD. We choose US = UD1 = UD2 = 0.9EF for the tunnel barriers. The conductance G+ (solid line) and G- (broken line) reflect the resonant tunneling through discrete energy levels formed in the QD region. Around some conductance peaks, e.g., at eVg/EF ≈ 0.13 and -0.03, the difference between G+ and G- is remarkably enhanced. Thus, a large spin current is observed, which implies that two energy levels are close to each other around the Fermi level there.


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

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

Results of the numerical simulation for the spin-filtering device shown in Fig. 1(b). The conductance G± for spin sz = ±1/2 from reservoir S to D1 is shown as a function of gate voltage Vg on the quantum dot. Solid and broken lines indicate G+ and G-, respectively. The height of the tunnel barriers is US = UD1 = UD2 = 0.9EF.
© Copyright Policy - open-access
Related In: Results  -  Collection

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

Figure 3: Results of the numerical simulation for the spin-filtering device shown in Fig. 1(b). The conductance G± for spin sz = ±1/2 from reservoir S to D1 is shown as a function of gate voltage Vg on the quantum dot. Solid and broken lines indicate G+ and G-, respectively. The height of the tunnel barriers is US = UD1 = UD2 = 0.9EF.
Mentions: Figure 3 presents the conductance G± for spin sz = ±1/2 as a function of the gate voltage Vg on the QD. We choose US = UD1 = UD2 = 0.9EF for the tunnel barriers. The conductance G+ (solid line) and G- (broken line) reflect the resonant tunneling through discrete energy levels formed in the QD region. Around some conductance peaks, e.g., at eVg/EF ≈ 0.13 and -0.03, the difference between G+ and G- is remarkably enhanced. Thus, a large spin current is observed, which implies that two energy levels are close to each other around the Fermi level there.

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