| 1. |
- Bernad, Joszef Zsolt, et al.
(författare)
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Effects of a quantum measurement on the electric conductivity : Application to graphene
- 2010
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Ingår i: Physical Review B. Condensed Matter and Materials Physics. - 1098-0121 .- 1550-235X. ; 81:7
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Tidskriftsartikel (refereegranskat)abstract
- We generalize the standard linear-response (Kubo) theory to obtain the conductivity of a system that is subject to a quantum measurement of the current. Our approach can be used to specifically elucidate how back-action inherent to quantum measurements affects electronic transport. To illustrate the utility of our general formalism, we calculate the frequency-dependent conductivity of graphene and discuss the effect of measurement-induced decoherence on its value in the dc limit. We are able to resolve an ambiguity related to the parametric dependence of the minimal conductivity.
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| 2. |
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| 3. |
- Grehk, Mikael, et al.
(författare)
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Li-induced phase transition from the Ge(111)3x1:Li surface reconstruction to the Ge(111)rot3xrot3:Li lithium germanid
- 2000
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Ingår i: Physical Review B. Condensed Matter and Materials Physics. - : American Physical Society. - 1098-0121 .- 1550-235X. ; 61:7, s. 4963-4967
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Tidskriftsartikel (refereegranskat)abstract
- We have investigated the Li-induced phase transition from the Ge(111)3×1:Li to the Ge(111)sqrt[3]×sqrt[3]:Li reconstruction with photoemission. The Ge(111)3×1:Li reconstruction can be described as parallel rows of Ge atoms separated by single rows of Li atoms. The Ge(111)sqrt[3]×sqrt[3]:Li reconstruction, on the other hands, has to be described in terms of a Li-germanide phase extending over at least two atomic layers.
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| 4. |
- Jääskeläinen, Markku, 1970-, et al.
(författare)
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Anomalous spin-related quantum phase in mesoscopic hole rings
- 2010
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Ingår i: Physical Review B. Condensed Matter and Materials Physics. - 1098-0121 .- 1550-235X. ; 81:15
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Tidskriftsartikel (refereegranskat)abstract
- We have obtained numerically exact results for the spin-related geometric quantum phases that arise in p-type semiconductor ring structures. The interplay between gate-controllable (Rashba) spin splitting and quantum-confinement-induced mixing between hole-spin states causes a much higher sensitivity of magnetoconductance oscillations to external parameters than previously expected. Our results imply a much-enhanced functionality of hole-ring spin-interference devices and shed new light on recent experimental findings.
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| 5. |
- Jääskeläinen, Markku, et al.
(författare)
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Quantum pumping of electrons by a moving modulated potential
- 2008
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Ingår i: Physical Review B. Condensed Matter and Materials Physics. - 1098-0121 .- 1550-235X. ; 77:15, s. 155319-
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Tidskriftsartikel (refereegranskat)abstract
- Quantum pumping holds great potential for future applications in microtechnology and nanotechnology. Its main feature, which is the dissipationless charge transport, is theoretically possible via several different mechanisms. However, since no unambiguous verification has been experimentally demonstrated, the question of finding a viable mechanism for pumping remains open. Here, we study quantum pumping in an one dimensional electron waveguide with a single time-dependent barrier. The quantum pumping of electrons by using a potential barrier whose height and position are harmonically varied is analytically analyzed and by numerically solving the time-dependent Schrodinger equation. The pumped charge is analytically modeled by including two contributions in linear response theory. First, the scattering of electrons off a potential moving slowly through matter waves gives a contribution independent of the translational velocity of the potential. Second, Doppler-shifted scattering events give rise to a velocity dependent contribution, which is found in general to be small in comparison with the first one. The relative phase between the oscillations of the height and position is found to be the factor that determines to what extent either contribution is present.
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| 6. |
- Stanciu, V., et al.
(författare)
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Influence of annealing parameters on the ferromagnetic properties of optimally passivated (Ga,Mn)As epilayers
- 2005
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Ingår i: Physical Review B. Condensed Matter and Materials Physics. - 1098-0121 .- 1550-235X. ; 72:12
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Tidskriftsartikel (refereegranskat)abstract
- The influence of annealing parameters—temperature (Ta) and time (ta)—on the magnetic properties of As-capped (Ga,Mn)As epitaxial thin films has been investigated. The dependence of the transition temperature (TC) on ta marks out two regions. The TC peak behavior, characteristic of the first region, is more pronounced for thick samples, while for the second ("saturated") region the effect of ta is more pronounced for thin samples. A right choice of the passivation medium, growth conditions along with optimal annealing parameters routinely yield TC-values of ~150 K and above, regardless of the thickness of the epilayers
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| 7. |
- Zivkovic, Marko, et al.
(författare)
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Sagnac rotational phase shifts in a mesoscopic electron interferometer with spin-orbit interactions
- 2008
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Ingår i: Physical Review B. Condensed Matter and Materials Physics. - 1098-0121 .- 1550-235X. ; 77:11
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Tidskriftsartikel (refereegranskat)abstract
- The Sagnac effect is an important phase coherent effect in optical and atom interferometers where rotations of the interferometer with respect to an inertial reference frame result in a shift in the interference pattern proportional to the rotation rate. Here, we analyze the Sagnac effect in a mesoscopic semiconductor electron interferometer. We include in our analysis the Rashba spin-orbit interactions in the ring. Our results indicate that spin-orbit interactions increase the rotation-induced phase shift. We discuss the potential experimental observability of the Sagnac phase shift in such mesoscopic systems.
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