| 1. |
- Aharony, A., et al.
(författare)
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Effects of Different Lead Magnetizations on the Datta-Das Spin Field-Effect Transistor
- 2019
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Ingår i: Journal of Physical Chemistry C. - : American Chemical Society (ACS). - 1932-7447 .- 1932-7455. ; 123:17, s. 11094-11100
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Tidskriftsartikel (refereegranskat)abstract
- A Datta-Das spin field-effect transistor is built of a one-dimensional weak link, with Rashba spin-orbit interactions (SOIs), which connects two magnetized reservoirs. The particle and spin currents between the two reservoirs are calculated to lowest order in the tunneling through the weak link and in the wide-band approximation, with emphasis on their dependence on the origins of the "bare" magnetizations in the reservoirs. The SOI is found to generate magnetization components in each reservoir, which rotate in the plane of the electric field (generating the SOI) and the weak link, only if the "bare" magnetization of the other reservoir has a nonzero component in that plane. The SOI affects the charge current only if both reservoirs are polarized. The charge current is conserved, but the transverse rotating magnetization current is not conserved because the SOI in the weak link generates extra spin polarizations which are injected into the reservoirs.
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| 2. |
- Aharony, A., et al.
(författare)
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Electric and magnetic gating of Rashba-active weak links
- 2018
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Ingår i: Physical Review B. - 2469-9950. ; 97:22
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Tidskriftsartikel (refereegranskat)abstract
- In a one-dimensional weak-link wire the spin-orbit interaction (SOI) alone cannot generate a nonzero spin current. We show that a Zeeman field acting in the wire in conjunction with the Rashba SOI there does yield such a current, whose magnitude and direction depend on the direction of the field. When this field is not parallel to the effective field due to the SOI, both the charge and the spin currents oscillate with the length of the wire. Measuring the oscillating anisotropic magnetoresistance can thus yield information on the SOI strength. These features are tuned by applying a magnetic and/or an electric field, with possible applications to spintronics.
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| 3. |
- Entin-Wohlman, O., et al.
(författare)
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Magnetization generated by microwave-induced Rashba interaction
- 2020
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Ingår i: Physical Review B. - 2469-9950. ; 102:7
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Tidskriftsartikel (refereegranskat)abstract
- We show that a controllable dc magnetization is accumulated in a junction comprising a quantum dot coupled to nonmagnetic reservoirs if the junction is subjected to a time-dependent spin-orbit interaction. The latter is induced by an ac electric field generated by microwave irradiation of the gated junction. The magnetization is caused by inelastic spin-flip scattering of electrons that tunnel through the junction, and depends on the polarization of the electric field: a circularly polarized field leads to the maximal effect, while there is no effect in a linearly polarized field. Furthermore, the magnetization increases as a step function (smoothened by temperature) as the microwave photon energy becomes larger than the absolute value of the difference between the single energy level on the quantum dot and the common chemical potential in the leads.
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| 4. |
- Entin-Wohlman, O., et al.
(författare)
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Magnetization near a constriction between BCS superconductors by spin-dependent tunneling
- 2023
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Ingår i: Physical Review B. - 2469-9950. ; 108:18
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Tidskriftsartikel (refereegranskat)abstract
- Spin-dependent electron tunneling through a voltage-biased microconstriction between two bulk superconductors is shown to create a dc component of the magnetization in the superconductors near the constriction and an ac Josephson-like spin current. The static magnetization appears in one superconductor even if the other is replaced by a normal conductor. Although spin-dependent tunneling generates quantum spin fluctuations also in the absence of a bias, the formation of spin-triplet Cooper pairs, necessary for the creation of magnetization, is blocked by destructive interference between different quasielectron and quasihole tunneling channels, unless there is an asymmetry between the tunneling densities of states for electrons and holes. Breaking the symmetry in the electron-hole tunnel density of states and creating electron-hole tunneling imbalance by biasing the device destroys the destructive interference and enables triplet Cooper-pair formation. As a result, magnetizing the superconductor becomes possible. The role of the voltage in lifting the blockade hindering the spin-triplet Cooper pair formation is an example of an electrically controlled dissipationless spintronic phenomenon.
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| 5. |
- Entin-Wohlman, O., et al.
(författare)
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Photovoltaic effect generated by spin-orbit interactions
- 2020
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Ingår i: Physical Review B. - 2469-9950. ; 101:12
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Tidskriftsartikel (refereegranskat)abstract
- An AC electric field applied to a junction comprising two spin-orbit coupled weak links connecting a quantum dot to two electronic terminals is proposed to induce a DC current and to generate a voltage drop over the junction if it is a part of an open circuit. This photovoltaic effect requires a junction in which mirror reflection symmetry is broken. Its origin lies in the different ways inelastic processes modify the reflection of electrons from the junction back into the two terminals, which leads to uncompensated DC transport. The effect can be detected by measuring the voltage drop that is built up due to that DC current. This voltage is an even function of the frequency of the AC electric field.
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| 6. |
- Entin-Wohlman, O., et al.
(författare)
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Rashba proximity states in superconducting tunnel junctions
- 2018
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Ingår i: Low Temperature Physics. - : AIP Publishing. - 1063-777X .- 1090-6517. ; 44:6, s. 543-551
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Tidskriftsartikel (refereegranskat)abstract
- We consider a new kind of superconducting proximity effect created by the tunneling of "spin split" Cooper pairs between two conventional superconductors connected by a normal conductor containing a quantum dot. The difference compared to the usual superconducting proximity effect is that the spin states of the tunneling Cooper pairs are split into singlet and triplet components by the electron spin-orbit coupling, which is assumed to be active in the normal conductor only. We demonstrate that the supercurrent carried by the spin-split Cooper pairs can be manipulated both mechanically and electrically for strengths of the spin-orbit coupling that can realistically be achieved by electrostatic gates. Published by AIP Publishing.
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| 7. |
- Jonson, Mats, 1947, et al.
(författare)
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DC spin generation by junctions with AC driven spin-orbit interaction
- 2019
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Ingår i: Physical Review B. - 2469-9950. ; 100:11
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Tidskriftsartikel (refereegranskat)abstract
- An unbiased one-dimensional weak link between two terminals, subjected to the Rashba spin-orbit interaction caused by an AC electric field which rotates periodically in the plane perpendicular to the link, is shown to inject spin-polarized electrons into the terminals. The injected spin polarization has a DC component along the link and a rotating transverse component in the perpendicular plane. In the low-rotation-frequency regime, these polarization components are proportional to the frequency. The DC component of the polarization vanishes for a linearly polarized electric field.
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| 8. |
- Jonson, Mats, 1947, et al.
(författare)
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Mechanically driven spin-orbit-active weak links
- 2018
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Ingår i: Fizika Nizkikh Temperatur. - : AIP Publishing. - 0132-6414. ; 44:12, s. 1577-1581
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Tidskriftsartikel (refereegranskat)abstract
- We show that new functionality of spin-orbit-active electronic weak links can be achieved by their time-dependent mechanical deformation. As an illustration we use a simple model to calculate the electronic spin current generated by rotating a bent spin-orbit-active nanowire coupled to bulk metallic leads. © Institute for Low Temperature Physics and Engineering. All rights reserved.
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| 9. |
- Sarkar, K., et al.
(författare)
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Effects of magnetic fields on the Datta-Das spin field-effect transistor
- 2020
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Ingår i: Physical Review B. - 2469-9950. ; 102:11
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Tidskriftsartikel (refereegranskat)abstract
- A Datta-Das spin field-effect transistor is built of a heterostructure with a Rashba spin-orbit interaction (SOI) at the interface (or quantum well) separating two possibly magnetized reservoirs. The particle and spin currents between the two reservoirs are driven by chemical potentials that are (possibly) different for each spin direction. These currents are also tuned by varying the strength of the SOI, which changes the amount of the rotation of the spins of electrons crossing the heterostructure. Here we investigate the dependence of these currents on additional Zeeman fields on the heterostructure and on variations of the reservoir magnetizations. In contrast to the particle current, the spin currents are not necessarily conserved; an additional spin polarization is injected into the reservoirs. If a reservoir has a finite (equilibrium) magnetization, then we surprisingly find that the spin current into that reservoir can only have spins which are parallel to the reservoir magnetization, independent of all the other fields. This spin current can be enhanced by increasing the magnetization of the other reservoir, and can also be tuned by the SOI and the various magnetic fields. When only one reservoir is magnetized then the spin current into the other reservoir has arbitrary tunable size and direction. In particular, this spin current changes as the magnetization of the other reservoir is rotated. The optimal conditions for accumulating spin polarization on an unpolarized reservoir are to either apply a Zeeman field in addition to the SOI, or to polarize the other reservoir.
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| 10. |
- Shekhter, Robert I., 1947, et al.
(författare)
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Magnetoconductance Anisotropies and Aharonov-Casher Phases
- 2022
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Ingår i: Physical Review Letters. - 0031-9007. ; 129:3
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Tidskriftsartikel (refereegranskat)abstract
- The spin-orbit interaction (SOI) is a key tool for manipulating and functionalizing spin-dependent electron transport. The desired function often depends on the SOI-generated phase that is accumulated by the wave function of an electron as it passes through the device. This phase, known as the Aharonov-Casher phase, therefore depends on both the device geometry and the SOI strength. Here, we propose a method for directly measuring the Aharonov-Casher phase generated in an SOI-active weak link, based on the Aharonov-Casher-phase dependent anisotropy of its magnetoconductance. Specifically, we consider weak links in which the Rashba interaction is caused by an external electric field, but our method is expected to apply also for other forms of the spin-orbit coupling. Measuring this magnetoconductance anisotropy thus allows calibrating Rashba spintronic devices by an external electric field that tunes the spin-orbit interaction and hence the Aharonov-Casher phase.
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