Direct Imaging of Electron States in Open Quantum Dots

Aoki, Nobuyuki; Brunner, Roland; Burke, Anthony M.; Akis, R.; Meisels, R.; Ferry, D. K.; Ochiai, Y.

doi:10.1103/physrevlett.108.136804

Cited by 36 publications

(32 citation statements)

References 24 publications

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“…In scanning gate microscopy (SGM) [16,17], a charged tip is scanned above the device of interest, and the effect of the induced potential fluctuation on the conductance in the device is monitored. Over the past few years, scanning gate microscopy has been used to investigate transport phenomena in a variety of low-dimensional systems like quantum dots [18][19][20][21], quantum-point contacts [22], and two-dimensional electron gases [23][24][25][26]. Of particular relevance to QSH edge-state transport, SGM has been applied to one-dimensional systems like carbon nanotubes [27,28] and nanowires [29], where it was used to identify and manipulate localized states that control the transport through the device.…”

Section: Experimental Methodsmentioning

confidence: 99%

Spatially Resolved Study of Backscattering in the Quantum Spin Hall State

et al. 2013

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The discovery of the quantum spin Hall (QSH) state, and topological insulators in general, has sparked strong experimental efforts. Transport studies of the quantum spin Hall state have confirmed the presence of edge states, showed ballistic edge transport in micron-sized samples, and demonstrated the spin polarization of the helical edge states. While these experiments have confirmed the broad theoretical model, the properties of the QSH edge states have not yet been investigated on a local scale. Using scanning gate microscopy to perturb the QSH edge states on a submicron scale, we identify well-localized scattering sites which likely limit the expected nondissipative transport in the helical edge channels. In the micron-sized regions between the scattering sites, the edge states appear to propagate unperturbed, as expected for an ideal QSH system, and are found to be robust against weak induced potential fluctuations.

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Section: Experimental Methodsmentioning

confidence: 99%

Spatially Resolved Study of Backscattering in the Quantum Spin Hall State

et al. 2013

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“…The interference of electron waves backscattered off the tip-depleted disc, off the QPC and impurities modulates the transmission probability of the latter and leads to the appearance of interference fringes along branches 2,3,18,22 . Scanning gate microscopy (SGM) studies have focused on completely open systems, such as quantum point contacts 2,3,[16][17][18][21][22][23][24][25][26][27][28][29] , and more closed systems, for example, cavities 19,[30][31][32][33][34][35] . In cavities irregular conductance fluctuations 19,[30][31][32] and regular fringes 19,35,36 originating from quantized tip-induced constrictions were observed.…”

Section: In Scanning Gatementioning

confidence: 99%

Electron backscattering in a cavity: Ballistic and coherent effects

et al. 2016

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Numerous experimental and theoretical studies have focused on low-dimensional systems locally perturbed by the biased tip of a scanning force microscope. In all cases either open or closed weakly gate-tunable nanostructures have been investigated, such as quantum point contacts, open or closed quantum dots, etc. We study the behaviour of the conductance of a quantum point contact with a gradually forming adjacent cavity in series under the influence of a scanning gate. Here, an initially open quantum point contact system gradually turns into a closed cavity system. We observe branches and interference fringes known from quantum point contacts coexisting with irregular conductance fluctuations. Unlike the branches, the fluctuations cover the entire area of the cavity. In contrast to previous studies, we observe and investigate branches under the influence of the confining stadium potential, which is gradually built up. We find that the branches exist only in the area surrounded by cavity top gates. As the stadium shrinks, regular fringes originate from tip-induced constrictions leading to quantized conduction. In addition, we observe arc-like areas reminiscent of classical electron trajectories in a chaotic cavity. We also argue that electrons emanating from the quantum point contact spread out like a fan leaving branch-like regions of enhanced backscattering.

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“…The read-heads of modern hard disk drives and non-volatile semiconductor memory devices such as magnetoresistive random access memory chips work on the basis of magnetic tunnel junctions. The study of spinpolarised electron transport through a molecular quantum dot coupled through tunnel barriers to ferromagnetic contacts has attracted considerable attention both experimentally and theoretically [1][2][3][4][5][6][7]. The giant magneto resistance and TMR effects were observed in systems with spinpolarised transport, including single and multi-walled carbon nanotubes, semiconductor quantum dots connected by a molecular bridge, organic thin films, self-assembled organic monolayers and so on [3,8].…”

Section: Introductionmentioning

confidence: 98%

Inelastic effect of electron–phonon interactions in tunnelling magnetoresistance of a single metallofullerene

2015

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The effects of elastic and inelastic electron-phonon interactions on current-voltage characteristic and tunnelling magnetoresistance (TMR) of Li@C 59 X (X = N, B) molecule that is coupled to two ferromagnetic electrodes was investigated using the non-equilibrium Green's function (NEGF) method. Our results by taking also into consideration spin degrees of freedom (excluding spin-mixing effects) indicate that the presence of inelastic electron-phonon interaction polaron formation increases current and shifts the TMR behaviour to higher values. Also, an increase of two orders of magnitude observed in current for Li@C 59 B compared to C 60 .

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Direct Imaging of Electron States in Open Quantum Dots

Cited by 36 publications

References 24 publications

Spatially Resolved Study of Backscattering in the Quantum Spin Hall State

Spatially Resolved Study of Backscattering in the Quantum Spin Hall State

Electron backscattering in a cavity: Ballistic and coherent effects

Inelastic effect of electron–phonon interactions in tunnelling magnetoresistance of a single metallofullerene

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