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Corfdir P, Marquardt O, Lewis RB, Sinito C, Ramsteiner M, Trampert A, Jahn U, Geelhaar L, Brandt O, Fomin VM. Excitonic Aharonov-Bohm Oscillations in Core-Shell Nanowires. ADVANCED MATERIALS (DEERFIELD BEACH, FLA.) 2019; 31:e1805645. [PMID: 30461088 DOI: 10.1002/adma.201805645] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/30/2018] [Revised: 10/15/2018] [Indexed: 06/09/2023]
Abstract
Phase coherence in nanostructures is at the heart of a wide range of quantum effects such as Josephson oscillations between exciton-polariton condensates in microcavities, conductance quantization in 1D ballistic transport, or the optical (excitonic) Aharonov-Bohm effect in semiconductor quantum rings. These effects only occur in structures of the highest perfection. The 2D semiconductor heterostructures required for the observation of Aharonov-Bohm oscillations have proved to be particularly demanding, since interface roughness or alloy fluctuations cause a loss of the spatial phase coherence of excitons, and ultimately induce exciton localization. Experimental work in this field has so far relied on either self-assembled ring structures with very limited control of shape and dimension or on lithographically defined nanorings that suffer from the detrimental effects of free surfaces. Here, it is demonstrated that nanowires are an ideal platform for studies of the Aharonov-Bohm effect of neutral and charged excitons, as they facilitate the controlled fabrication of nearly ideal quantum rings by combining all-binary radial heterostructures with axial crystal-phase quantum structures. Thanks to the atomically flat interfaces and the absence of alloy disorder, excitonic phase coherence is preserved even in rings with circumferences as large as 200 nm.
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Affiliation(s)
- Pierre Corfdir
- Paul-Drude-Institut für Festkörperelektronik, Leibniz-Institut im Forschungsverbund Berlin e. V., Hausvogteiplatz 5-7, 10117, Berlin, Germany
| | - Oliver Marquardt
- Paul-Drude-Institut für Festkörperelektronik, Leibniz-Institut im Forschungsverbund Berlin e. V., Hausvogteiplatz 5-7, 10117, Berlin, Germany
- Weierstraß-Institut für Angewandte Analysis und Stochastik, Leibniz-Institut im Forschungsverbund Berlin e. V., Mohrenstraße 39, 10117, Berlin, Germany
| | - Ryan B Lewis
- Paul-Drude-Institut für Festkörperelektronik, Leibniz-Institut im Forschungsverbund Berlin e. V., Hausvogteiplatz 5-7, 10117, Berlin, Germany
| | - Chiara Sinito
- Paul-Drude-Institut für Festkörperelektronik, Leibniz-Institut im Forschungsverbund Berlin e. V., Hausvogteiplatz 5-7, 10117, Berlin, Germany
| | - Manfred Ramsteiner
- Paul-Drude-Institut für Festkörperelektronik, Leibniz-Institut im Forschungsverbund Berlin e. V., Hausvogteiplatz 5-7, 10117, Berlin, Germany
| | - Achim Trampert
- Paul-Drude-Institut für Festkörperelektronik, Leibniz-Institut im Forschungsverbund Berlin e. V., Hausvogteiplatz 5-7, 10117, Berlin, Germany
| | - Uwe Jahn
- Paul-Drude-Institut für Festkörperelektronik, Leibniz-Institut im Forschungsverbund Berlin e. V., Hausvogteiplatz 5-7, 10117, Berlin, Germany
| | - Lutz Geelhaar
- Paul-Drude-Institut für Festkörperelektronik, Leibniz-Institut im Forschungsverbund Berlin e. V., Hausvogteiplatz 5-7, 10117, Berlin, Germany
| | - Oliver Brandt
- Paul-Drude-Institut für Festkörperelektronik, Leibniz-Institut im Forschungsverbund Berlin e. V., Hausvogteiplatz 5-7, 10117, Berlin, Germany
| | - Vladimir M Fomin
- Institute for Integrative Nanosciences, Leibniz IFW Dresden, Helmholtzstraße 20, 01069, Dresden, Germany
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da Costa DR, Chaves A, Ferreira WP, Farias GA, Ferreira R. Electronic properties of superlattices on quantum rings. JOURNAL OF PHYSICS. CONDENSED MATTER : AN INSTITUTE OF PHYSICS JOURNAL 2017; 29:165501. [PMID: 28218615 DOI: 10.1088/1361-648x/aa617e] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/06/2023]
Abstract
We present a theoretical study of the one-electron states of a semiconductor-made quantum ring (QR) containing a series of piecewise-constant wells and barriers distributed along the ring circumference. The single quantum well and the superlattice cases are considered in detail. We also investigate how such confining potentials affect the Aharonov-Bohm like oscillations of the energy spectrum and current in the presence of a magnetic field. The model is simple enough so as to allow obtaining various analytical or quasi-analytical results. We show that the well-in-a-ring structure presents enhanced localization features, as well as specific geometrical resonances in its above-barrier spectrum. We stress that the superlattice-in-a-ring structure allows giving a physical meaning to the often used but usually artificial Born-von-Karman periodic conditions, and discuss in detail the formation of energy minibands and minigaps for the circumferential motion, as well as several properties of the superlattice eigenstates in the presence of the magnetic field. We obtain that the Aharonov-Bohm oscillations of below-barrier miniband states are reinforced, owing to the important tunnel coupling between neighbour wells of the superlattice, which permits the electron to move in the ring. Additionally, we analysis a superlattice-like structure made of a regular distribution of ionized impurities placed around the QR, a system that may implement the superlattice in a ring idea. Finally, we consider several random disorder models, in order to study roughness disorder and to tackle the robustness of some results against deviations from the ideally nanostructured ring system.
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Affiliation(s)
- D R da Costa
- Departamento de Física, Universidade Federal do Ceará, Caixa Postal 6030, Campus do Pici, 60455-900 Fortaleza, Ceará, Brazil
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Chakraborty T, Manaselyan A, Barseghyan M. Irregular Aharonov-Bohm effect for interacting electrons in a ZnO quantum ring. JOURNAL OF PHYSICS. CONDENSED MATTER : AN INSTITUTE OF PHYSICS JOURNAL 2017; 29:075605. [PMID: 28035091 DOI: 10.1088/1361-648x/aa5168] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/06/2023]
Abstract
The electronic states and optical transitions of a ZnO quantum ring containing few interacting electrons in an applied magnetic field are found to be very different from those in a conventional semiconductor system, such as a GaAs ring. The strong Zeeman interaction and the Coulomb interaction of the ZnO system, two important characteristics of the electron system in ZnO, exert a profound influence on the electron states and on the optical properties of the ring. In particular, our results indicate that the Aharonov-Bohm (AB) effect in a ZnO quantum ring strongly depends on the electron number. In fact, for two electrons in the ZnO ring, the AB oscillations become aperiodic, while for three electrons (interacting) the AB oscillations completely disappear. Therefore, unlike in conventional quantum ring topology, here the AB effect (and the resulting persistent current) can be controlled by varying the electron number.
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Affiliation(s)
- Tapash Chakraborty
- Department of Physics and Astronomy, University of Manitoba, Winnipeg, R3T 2N2, Canada
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A solenoidal synthetic field and the non-Abelian Aharonov-Bohm effects in neutral atoms. Sci Rep 2014; 4:5992. [PMID: 25103877 PMCID: PMC4126000 DOI: 10.1038/srep05992] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/05/2013] [Accepted: 07/08/2014] [Indexed: 11/19/2022] Open
Abstract
Cold neutral atoms provide a versatile and controllable platform for emulating various quantum systems. Despite efforts to develop artificial gauge fields in these systems, realizing a unique ideal-solenoid-shaped magnetic field within the quantum domain in any real-world physical system remains elusive. Here we propose a scheme to generate a “hairline” solenoid with an extremely small size around 1 micrometer which is smaller than the typical coherence length in cold atoms. Correspondingly, interference effects will play a role in transport. Despite the small size, the magnetic flux imposed on the atoms is very large thanks to the very strong field generated inside the solenoid. By arranging different sets of Laguerre-Gauss (LG) lasers, the generation of Abelian and non-Abelian SU(2) lattice gauge fields is proposed for neutral atoms in ring- and square-shaped optical lattices. As an application, interference patterns of the magnetic type-I Aharonov-Bohm (AB) effect are obtained by evolving atoms along a circle over several tens of lattice cells. During the evolution, the quantum coherence is maintained and the atoms are exposed to a large magnetic flux. The scheme requires only standard optical access, and is robust to weak particle interactions.
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Chwiej T, Szafran B. Fractional conductance oscillations in quantum rings: wave packet picture of transport in a few-electron system. JOURNAL OF PHYSICS. CONDENSED MATTER : AN INSTITUTE OF PHYSICS JOURNAL 2013; 25:155802. [PMID: 23529068 DOI: 10.1088/0953-8984/25/15/155802] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/02/2023]
Abstract
We study electron transfer across a two-terminal quantum ring using a time-dependent description of the scattering process. For the considered scattering event the quantum ring is initially charged with one or two electrons, with another electron incident to the ring from the input channel. We study the electron transfer probability (T) as a function of the external magnetic field. We determine the periodicity of T for a varied number of electrons confined within the ring. For that purpose we develop a method to describe the wave packet dynamics for a few electrons participating in the scattering process, taking into full account the electron-electron correlations. We find that electron transfer across the quantum ring initially charged by a single electron acquires a distinct periodicity of half of the magnetic flux quantum (Φ0/2), corresponding to the formation of a transient two-electron state inside the ring. In the case of a three-electron scattering problem with two electrons initially occupying the ring, a period of Φ0/3 for T is formed in the limit of thin channels. The effect of disorder present in the confinement potential of the ring is also discussed.
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Affiliation(s)
- T Chwiej
- AGH University of Science and Technology, Faculty of Physics and Applied Computer Science, al. Mickiewicza 30, 30-059 Kraków, Poland
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6
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See AM, Pilgrim I, Scannell BC, Montgomery RD, Klochan O, Burke AM, Aagesen M, Lindelof PE, Farrer I, Ritchie DA, Taylor RP, Hamilton AR, Micolich AP. Impact of small-angle scattering on ballistic transport in quantum dots. PHYSICAL REVIEW LETTERS 2012; 108:196807. [PMID: 23003076 DOI: 10.1103/physrevlett.108.196807] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/22/2011] [Revised: 03/08/2012] [Indexed: 06/01/2023]
Abstract
Disorder increasingly affects performance as electronic devices are reduced in size. The ionized dopants used to populate a device with electrons are particularly problematic, leading to unpredictable changes in the behavior of devices such as quantum dots each time they are cooled for use. We show that a quantum dot can be used as a highly sensitive probe of changes in disorder potential and that, by removing the ionized dopants and populating the dot electrostatically, its electronic properties become reproducible with high fidelity after thermal cycling to room temperature. Our work demonstrates that the disorder potential has a significant, perhaps even dominant, influence on the electron dynamics, with important implications for "ballistic" transport in quantum dots.
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Affiliation(s)
- A M See
- School of Physics, University of New South Wales, Sydney NSW 2052, Australia
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7
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Tkachenko OA, Tkachenko VA, Kvon ZD, Aseev AL, Portal JC. Quantum interferential Y-junction switch. NANOTECHNOLOGY 2012; 23:095202. [PMID: 22327287 DOI: 10.1088/0957-4484/23/9/095202] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/31/2023]
Abstract
We report the observation of the Fermi energy controlled redirection of the ballistic electron flow in a three-terminal system based on a small (100 nm) triangular quantum dot defined in a two-dimensional electron gas (2DEG). Measurement shows strong large-scale sign-changing oscillations of the partial conductance coefficient difference G(21) - G(23) on the gate voltage in zero magnetic field. Simple formulas and numerical simulation show that the effect can be explained by quantum interference and is associated with weak asymmetry of the dot or inequality of the ports connecting the dot to the 2DEG reservoirs. The effect may be strengthened by a weak perpendicular magnetic field. We also consider an additional three-terminal system in which the direction of the electron flow can be controlled by the voltage on the scanning gate microscopy (SGM) tip.
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Affiliation(s)
- O A Tkachenko
- A V Rzhanov Institute of Semiconductor Physics SB RAS, Novosibirsk, Russia.
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8
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Micolich AP. What lurks below the last plateau: experimental studies of the 0.7 × 2e(2)/h conductance anomaly in one-dimensional systems. JOURNAL OF PHYSICS. CONDENSED MATTER : AN INSTITUTE OF PHYSICS JOURNAL 2011; 23:443201. [PMID: 21997403 DOI: 10.1088/0953-8984/23/44/443201] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/31/2023]
Abstract
The integer quantised conductance of one-dimensional electron systems is a well-understood effect of quantum confinement. A number of fractionally quantised plateaus are also commonly observed. They are attributed to many-body effects, but their precise origin is still a matter of debate, having attracted considerable interest over the past 15 years. This review reports on experimental studies of fractionally quantised plateaus in semiconductor quantum point contacts and quantum wires, focusing on the 0.7 × 2e(2)/h conductance anomaly, its analogues at higher conductances and the zero-bias peak observed in the dc source-drain bias for conductances less than 2e(2)/h.
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Affiliation(s)
- A P Micolich
- School of Physics, University of New South Wales, Sydney, NSW 2052, Australia.
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9
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Liang S, Xie W, Sarkisyan HA, Meliksetyan AV, Shen H. Nonlinear optical properties in a nanoring: quantum size and magnetic field effect. JOURNAL OF PHYSICS. CONDENSED MATTER : AN INSTITUTE OF PHYSICS JOURNAL 2011; 23:415302. [PMID: 21952507 DOI: 10.1088/0953-8984/23/41/415302] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/31/2023]
Abstract
We have studied the nonlinear optical absorption and the nonlinear optical rectification of an exciton in a nanoring in the presence of magnetic flux. The calculation results show that one can control the properties of nonlinear optical absorption and nonlinear optical rectification of a nanoring by tuning the outer and inner radius. Moreover, we find that the nonlinear optical properties of a nanoring can be modulated by the magnetic flux through the nanoring.
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Affiliation(s)
- Shijun Liang
- Department of Physics, College of Physics and Electronic Engineering, Guangzhou University, Guangzhou 510006, People's Republic of China. shijun
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10
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11
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Poniedziałek MR, Szafran B. Magnetic forces and stationary electron flow in a three-terminal semiconductor quantum ring. JOURNAL OF PHYSICS. CONDENSED MATTER : AN INSTITUTE OF PHYSICS JOURNAL 2010; 22:215801. [PMID: 21393725 DOI: 10.1088/0953-8984/22/21/215801] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/30/2023]
Abstract
We study stationary electron flow through a three-terminal quantum ring and describe effects due to deflection of electron trajectories by classical magnetic forces. We demonstrate that generally at high magnetic field (B) the current is guided by magnetic forces to follow a classical path, which for B > 0 leads via the left arm of the ring to the left output terminal. The transport to the left output terminal is blocked for narrow windows of magnetic field for which the interference within the ring leads to formation of wavefunctions that are only weakly coupled to the output channel wavefunctions. These interference conditions are accompanied by injection of the current to the right arm of the ring and by appearance of sharp peaks of the transfer probability to the right output terminal. We find that these peaks at high magnetic field are attenuated by thermal widening of the transport window. We also demonstrate that the interference conditions that lead to their appearance vanish when elastic scattering within the ring is present. The clear effect of magnetic forces on the transfer probabilities disappears along with Aharonov-Bohm oscillations in a chaotic transport regime that is found for rings whose width is larger than the width of the channels.
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Affiliation(s)
- M R Poniedziałek
- Faculty of Physics and Applied Computer Science, AGH University of Science and Technology, aleja Mickiewicza 30, 30-059 Kraków, Poland
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Jung M, Lee JS, Song W, Kim YH, Lee SD, Kim N, Park J, Choi MS, Katsumoto S, Lee H, Kim J. Quantum interference in radial heterostructure nanowires. NANO LETTERS 2008; 8:3189-3193. [PMID: 18767885 DOI: 10.1021/nl801506w] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/26/2023]
Abstract
Core/shell heterostructure nanowires are one of the most interesting mesoscopic systems potentially suitable for the study of quantum interference phenomena. Here, we report on experimental observations of both the Aharonov-Bohm (h/e) and the Altshuler-Aronov-Spivak (h/2e) oscillations in radial core/shell (In2O3/InOx) heterostructure nanowires. For a long channel device with a length-to-width ratio of about 33, the magnetoresistance curves at low temperatures exhibited a crossover from low-field h/2e oscillation to high-field h/ e oscillation. The relationship between the oscillation period and the core width was investigated for freestanding or substrate-supported devices and indicated that the current flows dominantly through the core/shell interface.
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Affiliation(s)
- Minkyung Jung
- National Creative Research Initiative, Center for Smart Molecular Memory, Electronics and Telecommunication Research Institute, Daejeon 305-700, Korea
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Hod O, Baer R, Rabani E. Magnetoresistance of nanoscale molecular devices based on Aharonov-Bohm interferometry. JOURNAL OF PHYSICS. CONDENSED MATTER : AN INSTITUTE OF PHYSICS JOURNAL 2008; 20:383201. [PMID: 21693808 DOI: 10.1088/0953-8984/20/38/383201] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/30/2023]
Abstract
Control of conductance in molecular junctions is of key importance in the growing field of molecular electronics. The current in these junctions is often controlled by an electric gate designed to shift conductance peaks into the low bias regime. Magnetic fields, on the other hand, have rarely been used due to the small magnetic flux captured by molecular conductors (an exception is the Kondo effect in single-molecule transistors). This is in contrast to a related field, electronic transport through mesoscopic devices, where considerable activity with magnetic fields has led to a rich description of transport. The scarcity of experimental activity is due to the belief that significant magnetic response is obtained only when the magnetic flux is of the order of the quantum flux, while attaining such a flux for molecular and nanoscale devices requires unrealistic magnetic fields. Here we review recent theoretical work regarding the essential physical requirements necessary for the construction of nanometer-scale magnetoresistance devices based on an Aharonov-Bohm molecular interferometer. We show that control of the conductance properties using small fractions of a magnetic flux can be achieved by carefully adjusting the lifetime of the conducting electrons through a pre-selected single state that is well separated from other states due to quantum confinement effects. Using a simple analytical model and more elaborate atomistic calculations we demonstrate that magnetic fields which give rise to a magnetic flux comparable to 10(-3) of the quantum flux can be used to switch a class of different molecular and nanometer rings, ranging from quantum corrals, carbon nanotubes and even a molecular ring composed of polyconjugated aromatic materials. The unique characteristics of the magnetic field as a gate is further discussed and demonstrated in two different directions. First, a three-terminal molecular router devices that can function as a parallel logic gate, processing two logic operations simultaneously, is presented. Second, the role of inelastic effects arising from electron-phonon couplings on the magnetoresistance properties is analyzed. We show that a remarkable difference between electric and magnetic gating is also revealed when inelastic effects become significant. The inelastic broadening of response curves to electric gates is replaced by a narrowing of magnetoconductance peaks, thereby enhancing the sensitivity of the device.
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Affiliation(s)
- Oded Hod
- Department of Chemistry, Rice University, Houston, TX 77005-1892, USA
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Tong CZ, Yoon SF. Investigation of the fabrication mechanism of self-assembled GaAs quantum rings grown by droplet epitaxy. NANOTECHNOLOGY 2008; 19:365604. [PMID: 21828875 DOI: 10.1088/0957-4484/19/36/365604] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/31/2023]
Abstract
We have directly imaged the formation of a GaAs quantum ring (QR) using droplet epitaxy followed by annealing in arsenic ambient. Based on the atomic force micrograph measurement and the analysis of surface energy, we determine that the formation of self-assembled GaAs QRs is due to the gallium atom's diffusion and crystallization driven by the gradient of surface energy. The phenomenon that GaAs is etched by the gallium droplets is reported and analyzed. It has been demonstrated that the epitaxy layers, such as AlAs and InGaP, can be used as the etching stop layer and hence can be used to control the shape and height of the QRs.
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Affiliation(s)
- C Z Tong
- School of Electrical and Electronic Engineering, Nanyang Technological University, Singapore 639798, Republic of Singapore
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15
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Neder I, Ginossar E. Behavior of electronic interferometers in the nonlinear regime. PHYSICAL REVIEW LETTERS 2008; 100:196806. [PMID: 18518476 DOI: 10.1103/physrevlett.100.196806] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/08/2007] [Indexed: 05/26/2023]
Abstract
We investigate theoretically the behavior of the current oscillations in an electronic Mach-Zehnder interferometer (MZI) as a function of its source bias. Recently, the MZI visibility data showed an unexplained lobe pattern with a peculiar phase rigidity. Moreover, the effect did not depend on the MZI path length difference. We argue that these effects may be a new many-body manifestation of particle-wave duality in quantum mechanics. When biasing the interferometer sources so much that multiple electrons are on each arm at any instant in time, quantum shot noise (a particle phenomena) must affect the interference pattern of the electrons that create it. A solution to the interaction Hamiltonian presented here shows that the interference visibility has a lobe pattern with applied bias that has a period proportional to the average path length and independent of the path length difference, together with a phase rigidity.
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Affiliation(s)
- I Neder
- Department of Condensed Matter Physics, The Weizmann Institute of Science, Rehovot, Israel.
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Sellers IR, Whiteside VR, Kuskovsky IL, Govorov AO, McCombe BD. Aharonov-Bohm excitons at elevated temperatures in type-II ZnTe/ZnSe quantum dots. PHYSICAL REVIEW LETTERS 2008; 100:136405. [PMID: 18517978 DOI: 10.1103/physrevlett.100.136405] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/23/2007] [Revised: 02/13/2008] [Indexed: 05/26/2023]
Abstract
Optical emission from type-II ZnTe/ZnSe quantum dots demonstrates large and persistent oscillations in both the peak energy and intensity indicating the formation of coherently rotating states. Furthermore, these Aharonov-Bohm oscillations are shown to be remarkably robust and persist until 180 K. This is at least one order of magnitude greater than the typical temperatures in lithographically defined rings. To our knowledge, this is the highest temperature at which the AB effect has been observed in solid-state and molecular nanostructures.
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Affiliation(s)
- I R Sellers
- Department of Physics, Fronczak Hall, University at Buffalo SUNY, Buffalo, New York 14260, USA.
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18
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Hod O, Baer R, Rabani E. Inelastic effects in Aharonov-Bohm molecular interferometers. PHYSICAL REVIEW LETTERS 2006; 97:266803. [PMID: 17280449 DOI: 10.1103/physrevlett.97.266803] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/25/2006] [Indexed: 05/13/2023]
Abstract
Inelastic effects arising from electron-phonon coupling in molecular Aharonov-Bohm (AB) interferometers are studied using the nonequilibrium Green's function method. Results for the magnetoconductance are compared for different values of the electron-phonon coupling strength. At low-bias voltages, the coupling to the phonons does not change the lifetime and leads mainly to scattering phase shifts of the conducting electrons. As a result of these dephasing processes, the magnetoconductance of the molecular AB interferometer becomes more sensitive to the threading magnetic flux as the electron-phonon coupling is increased, opposite to the behavior of an electric gate.
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Affiliation(s)
- Oded Hod
- School of Chemistry, Tel Aviv University, Tel Aviv 69978, Israel
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Abstract
Affecting the current through a molecular or nanoscale junction is usually done by a combination of bias and gate voltages. Magnetic fields are less studied because nanodevices can capture only low values of the magnetic flux. We review recent work done with the aim of finding the conditions for magnetic fields to significantly affect the conductance of such junctions. The basic idea is to create narrow tunneling resonances through a molecular ring-like structure that are highly sensitive to the magnetic field. We describe a computational method that allows us to examine atomistic models of such systems and discuss several specific examples of plausible systems, such as the quantum corral, carbon nanotubes, and polycyclic aromatic hydrocarbon molecules. A unique property of the magnetic field, namely, its ability to split degenerate levels on the ring, is shown to allow prototypes of interesting new nanoscale devices, such as the three-terminal parallel logic gate.
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Affiliation(s)
- Oded Hod
- School of Chemistry, The Sackler Faculty of Exact Science, Tel Aviv University, Tel Aviv 69978, Israel
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Affiliation(s)
- Oded Hod
- School of Chemistry, The Sackler Faculty of Exact Science, Tel Aviv University, Tel Aviv 69978, Israel, and Department of Physical Chemistry and the Lise Meitner Center for Quantum Chemistry, The Hebrew University of Jerusalem, Jerusalem 91904, Israel
| | - Roi Baer
- School of Chemistry, The Sackler Faculty of Exact Science, Tel Aviv University, Tel Aviv 69978, Israel, and Department of Physical Chemistry and the Lise Meitner Center for Quantum Chemistry, The Hebrew University of Jerusalem, Jerusalem 91904, Israel
| | - Eran Rabani
- School of Chemistry, The Sackler Faculty of Exact Science, Tel Aviv University, Tel Aviv 69978, Israel, and Department of Physical Chemistry and the Lise Meitner Center for Quantum Chemistry, The Hebrew University of Jerusalem, Jerusalem 91904, Israel
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Ribeiro E, Govorov AO, Carvalho W, Medeiros-Ribeiro G. Aharonov-Bohm signature for neutral polarized excitons in type-II quantum dot ensembles. PHYSICAL REVIEW LETTERS 2004; 92:126402. [PMID: 15089692 DOI: 10.1103/physrevlett.92.126402] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/03/2003] [Indexed: 05/24/2023]
Abstract
The Aharonov-Bohm effect is commonly believed to be a typical feature of the motion of a charged particle interacting with the electromagnetic vector potential. Here we present a magnetophotoluminescence study of type-II InP/GaAs self-assembled quantum dots, revealing the Aharonov-Bohm-type oscillations for neutral excitons when the hole ground state changes its angular momentum from l(h)=0 to l(h)=1, 2, and 3. The hole-ring parameters derived from a simple model are in excellent agreement with the structural parameters for this system.
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Affiliation(s)
- E Ribeiro
- Laboratório Nacional de Luz Síncrotron, P.O. Box 6192, 13084-971 Campinas-SP, Brazil.
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Fuhrer A, Lüscher S, Ihn T, Heinzel T, Ensslin K, Wegscheider W, Bichler M. Energy spectra of quantum rings. Nature 2001; 413:822-5. [PMID: 11677600 DOI: 10.1038/35101552] [Citation(s) in RCA: 81] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
Quantum mechanical experiments in ring geometries have long fascinated physicists. Open rings connected to leads, for example, allow the observation of the Aharonov-Bohm effect, one of the best examples of quantum mechanical phase coherence. The phase coherence of electrons travelling through a quantum dot embedded in one arm of an open ring has also been demonstrated. The energy spectra of closed rings have only recently been studied by optical spectroscopy. The prediction that they allow persistent current has been explored in various experiments. Here we report magnetotransport experiments on closed rings in the Coulomb blockade regime. Our experiments show that a microscopic understanding of energy levels, so far limited to few-electron quantum dots, can be extended to a many-electron system. A semiclassical interpretation of our results indicates that electron motion in the rings is governed by regular rather than chaotic motion, an unexplored regime in many-electron quantum dots. This opens a way to experiments where even more complex structures can be investigated at a quantum mechanical level.
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Affiliation(s)
- A Fuhrer
- Solid State Physics Laboratory, ETH Zürich, 8093 Zürich, Switzerland
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Park KW, Lee S, Shin M, Lee EH, Kwon HC. Electron interference due to localization paths in an Aharonov-Bohm ring. PHYSICAL REVIEW. B, CONDENSED MATTER 1996; 54:1498-1501. [PMID: 9985982 DOI: 10.1103/physrevb.54.1498] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 04/12/2023]
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Tan W, Inkson JC. Landau quantization and the Aharonov-Bohm effect in a two-dimensional ring. PHYSICAL REVIEW. B, CONDENSED MATTER 1996; 53:6947-6950. [PMID: 9982129 DOI: 10.1103/physrevb.53.6947] [Citation(s) in RCA: 57] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 04/12/2023]
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Liu J, Gao WX, Ismail K, Lee KY, Hong JM, Washburn S. Correlations between Aharonov-Bohm effects and one-dimensional subband populations in GaAs/AlxGa1-xAs rings. PHYSICAL REVIEW. B, CONDENSED MATTER 1993; 48:15148-15157. [PMID: 10008049 DOI: 10.1103/physrevb.48.15148] [Citation(s) in RCA: 23] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 04/12/2023]
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