| 1. |
- Fasth, Carina, et al.
(författare)
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Direct Measurement of the Spin-Orbit Interaction in a Two-Electron InAs Nanowire Quantum Dot
- 2007
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Ingår i: Physical Review Letters. - 1079-7114. ; 98, s. 1-266801
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Tidskriftsartikel (refereegranskat)abstract
- We demonstrate control of the electron number down to the last electron in tunable few-electron quantum dots defined in catalytically grown InAs nanowires. Using low temperature transport spectroscopy in the Coulomb blockade regime, we propose a method to directly determine the magnitude of the spin-orbit interaction in a two-electron artificial atom with strong spin-orbit coupling. Because of a large effective g factor |g*|=8±1, the transition from a singlet S to a triplet T+ ground state with increasing magnetic field is dominated by the Zeeman energy rather than by orbital effects. We find that the spin-orbit coupling mixes the T+ and S states and thus induces an avoided crossing with magnitude ΔSO=0.25±0.05 meV. This allows us to calculate the spin-orbit length λSO≈127 nm in such systems using a simple model.
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| 2. |
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| 3. |
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| 4. |
- Fasth, Carina, et al.
(författare)
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Tunable double quantum dots in InAs nanowires defined by local gate electrodes
- 2005
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Ingår i: Nano Letters. - : American Chemical Society (ACS). - 1530-6992 .- 1530-6984. ; 5:7, s. 1487-1490
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Tidskriftsartikel (refereegranskat)abstract
- We report on low-temperature transport measurements on single and double quantum dots defined using local gates to electrostatically deplete InAs nanowires grown by chemical beam epitaxy. This technique allows us to define multiple quantum dots along a semiconducting nanowire and tune the coupling between them.
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| 5. |
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| 6. |
- Fuhrer, Andreas, et al.
(författare)
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Single electron pumping in InAs nanowire double quantum dots
- 2007
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Ingår i: Applied Physics Letters. - : AIP Publishing. - 0003-6951 .- 1077-3118. ; 91:5, s. 1-052109
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Tidskriftsartikel (refereegranskat)abstract
- Closely spaced local gate electrodes are used to electrically define a double quantum dot along an InAs nanowire crystal. By applying a periodic pulse sequence to two plunger gate electrodes controlling the double quantum dot charge configuration, the device is operated as a single electron pump. The authors find that within measurement accuracy, the pumping current equals one electron per cycle for frequencies up to 2 MHz, demonstrating the suitability of nanowire based quantum dots for pumping applications.
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| 7. |
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| 8. |
- Fuhrer, Andreas, et al.
(författare)
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Transport studies on nanowire quantum dots
- 2005
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Ingår i: Book of extended abstracts: Niels Bohr Summer School, Copenhagen, Denmark (2005), invited.
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Konferensbidrag (refereegranskat)
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| 9. |
- Hansen, Adam, et al.
(författare)
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Spin relaxation in InAs nanowires studied by tunable weak antilocalization
- 2005
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Ingår i: Physical Review B. Condensed Matter and Materials Physics. ; 71, s. 1-205328
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Tidskriftsartikel (refereegranskat)abstract
- We report on a low-temperature magnetoconductance study to characterize the electrical and spin transport properties of n-type InAs nanowires grown by chemical beam epitaxy. A gate-controlled crossover from weak localization to weak antilocalization is observed. The measured magnetoconductance data agrees well with theory for one-dimensional quasi-ballistic systems and yields a spin relaxation length which decreases with increasing gate voltage.
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| 10. |
- Roddaro, Stefano, et al.
(författare)
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Spin States of holes in ge/si nanowire quantum dots.
- 2008
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Ingår i: Physical Review Letters. - 1079-7114. ; 101:18
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Tidskriftsartikel (refereegranskat)abstract
- We investigate tunable hole quantum dots defined by surface gating Ge/Si core-shell nanowire heterostructures. In single level Coulomb-blockade transport measurements at low temperatures spin doublets are found, which become sequentially filled by holes. Magnetotransport measurements allow us to extract a g factor g;{*} approximately 2 close to the value of a free spin-1/2 particle in the case of the smallest dot. In less confined quantum dots smaller g factor values are observed. This indicates a lifting of the expected strong spin-orbit interaction effects in the valence band for holes confined in small enough quantum dots. By comparing the excitation spectrum with the addition spectrum we tentatively identify a hole exchange interaction strength chi approximately 130 mueV.
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