Quantum Interference in Radial Heterostructure Nanowires

Jung, Minkyung; Lee, Joon Sung; Song, Woon; Kim, Young Heon; Kim, Nam; Park, Jeunghee; Choi, Myung Suk; Katsumoto, Shingo; Lee, Hyoyoung; Kim, Jinhee

doi:10.1021/nl801506w

Cited by 28 publications

(34 citation statements)

References 29 publications

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“…In tubular wires, such as carbon nanotubes, and InN nanowires in which only surface electrons conduct, 45 and radial core-shell InO nanowires, 46 the tubular topology of the electron system can be taken into account by periodic boundary conditions. In the following, we focus on wires where the dominant SO coupling is of Rashba type.…”

Section: Tubular Wiresmentioning

confidence: 99%

Dimensional dependence of weak localization corrections and spin relaxation in quantum wires with Rashba spin-orbit coupling

Wenk

Kettemann

2010

Phys. Rev. B

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The quantum correction to the conductivity in disordered quantum wires with linear Rashba spin-orbit coupling is obtained. For quantum wires with spin-conserving boundary conditions, we find a crossover from weak antilocalization to weak localization as the wire width W is reduced using exact diagonalization of the Cooperon equation. This crossover is due to the dimensional dependence of the spin relaxation rate of conduction electrons, which becomes diminished, when the wire width W is smaller than the bulk spin precession length L SO . We thus confirm previous results for small wire width, W / L SO Շ 1 ͓S. Kettemann, Phys. Rev. Lett. 98, 176808 ͑2007͔͒, where only the transverse 0 modes of the Cooperon equation had been taken into account. We find that spin helix solutions become stable for arbitrary ratios of linear Rashba and Dresselhaus coupling in narrow wires. For wider wires, the spin relaxation rate is found to be not monotonous as function of wire width W: it becomes first enhanced for W on the order of the bulk spin precession length L SO before it becomes diminished for smaller wire widths. In addition, we find that the spin relaxation is smallest at the edge of the wire for wide wires. The effect of the Zeeman coupling to the magnetic field perpendicular to the 2D electron system ͑2DES͒ is studied and found to result in a modification of the magnetoconductivity: it shifts the crossover from weak antilocalization to weak localization to larger wire widths W c . When the transverse confinement potential of the quantum wire is smooth, the boundary conditions become rather adiabatic. Then, the spin relaxation rate is found to be enhanced as the wire width W is reduced. We find that only a spinpolarized state retains a finite spin relaxation rate in such narrow wires. Thus, we conclude that the injection of polarized spins into nonmagnetic quantum wires should be favorable in wires with smooth confinement potential. Finally, in wires with tubular shape, corresponding to transverse periodic boundary conditions, we find no reduction of the spin relaxation rate.

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Section: Tubular Wiresmentioning

confidence: 99%

Dimensional dependence of weak localization corrections and spin relaxation in quantum wires with Rashba spin-orbit coupling

Wenk

Kettemann

2010

Phys. Rev. B

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“…In particular, an axial field may lead to Aharonov-Bohm (AB) field-periodic modulation of the electron energy spectrum [11] and, if the phase-coherent length exceeds the perimeter of the NW, the observation of magnetoconductance oscillations [12,13]. Indeed, several observations of AB-like oscillations in magnetotransport experiments performed on radial heterostructures have been reported [14][15][16][17][18]. Recently, Gül et al [16] observed fluxperiodic magnetoconductance oscillations in GaAs/InAs coreshell NWs.…”

Section: Introductionmentioning

confidence: 99%

Aharonov-Bohm oscillations and electron gas transitions in hexagonal core-shell nanowires with an axial magnetic field

et al. 2015

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We use spin-density-functional theory within an envelope function approach to calculate electronic states in a GaAs/InAs core-shell nanowire pierced by an axial magnetic field. Our fully three-dimensional quantum modeling includes explicitly a description of the realistic cross section and composition of the sample, and the electrostatic field induced by external gates in two different device geometries: gate-all-around and back-gate. At low magnetic fields, we investigate Aharonov-Bohm oscillations and signatures therein of the discrete symmetry of the electronic system, and we critically analyze recent magnetoconductance observations. At high magnetic fields, we find that several charge and spin transitions occur. We discuss the origin of these transitions in terms of different localization and Coulomb regimes, and we predict their signatures in magnetoconductance experiments.

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“…When the ON state was switched back to the OFF state by a positive voltage pulse applied at an amplitude of + 2.0 V, this OFF state was sustained even after 390 s with little degradation. Conversely, in the case of shorter alkyl chains (3 a), the retention time was reduced to near 200 s. For the application of MMNVM, the retention time of Ru complex 3 b remained sufficiently large compared with that of DRAM (a few milliseconds), and, furthermore, the retention time of 3 b could be extended to several days by utilizing a nanowire as a channel, [21] as shown in our previous report with 2 a. [22] In addition, the ratio between the probe currents corresponded to the ON/OFF ratio obtained in the I-V characteristics, as depicted in Figure 2.…”

mentioning

confidence: 99%

Molecular Monolayer Nonvolatile Memory with Tunable Molecules

et al. 2009

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With the development of the information industry, computer chips play a central role in information storage and have become highly integrated. Currently, there is increasing interest in the use of organic and polymer materials as nonvolatile memory elements.[1] Organic nonvolatile memory is a possible substitute for volatile dynamic random access memory (DRAM), which typically requires a data refresh every few milliseconds, and has the advantage of very low power consumption. However, limitations of the nanoscaled device fabrication of vapor-deposited organic resistive random access memory (ORRAM) [2] and spin-coated polymer resistive random access memory (PORAM) [3] have led to increased importance of molecular monolayer memory using organic self-assembled monolayers (SAMs). Several research groups have developed possible voltage-driven molecular memory devices possessing the advantages of fast response time and highly dense circuits over a photodriven circuit, [4] using a molecular monolayer for metal-molecule-metal (MMM) devices.[5] However, the use of molecular monolayers has been limited by low device yields, which are mainly attributed to electrical shorting, [6] especially for voltagedriven devices. As the top metal electrode is deposited onto the molecular monolayer, energetic metal atoms can degrade the SAM molecules, [7] and metal particles often penetrate the molecular monolayers to form metallic current paths.[8] To reduce the degree of electrical shorting, the following issues have been considered: the compactness and robustness of Langmuir-Blodgett (LB) films [9] and SAMs; [10] the use of bilayer SAMs; [11] a metal electrode with a nanosized surface area; [12] reduction of the surface roughness of the metal electrode;[13] a Pd nanowire [14] or single-walled carbon nanotube [15] as a substitute for the top metal electrode; and the use of a conducting polymer layer (PEDOT:PSS) [16] as a soft portion of the top metal electrode on the molecular monolayer. Although various prototype molecular monolayer memory devices, including a photodriven example, [4] have been introduced, there are very few reports on molecular monolayer nonvolatile memory (MMNVM). For the fabrication of MMNVM, the design of redox-active molecular memory SAM materials becomes a critical factor, especially for the development of a voltage-driven MMNVM that requires direct contact measurement of the memory effect through a molecular monolayer between the bottom and top electrodes. It was recently demonstrated by scanning tunneling microscopy (STM) that Ru II terpyridine complexes without alkyl chains-metal-to-ligand charge-transfer (MLCT) complexes-have a voltage-driven molecular switch in the solid-state molecular junction. [17] In the fabrication of a molecular monolayer memory device, however, the direct use of Ru II terpyridine complexes without alkyl chains results in electrical shorting. In an implementation of molecular monolayer memory circuits with high yield, it is important to reduce the electrical shorting by modifying the...

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Quantum Interference in Radial Heterostructure Nanowires

Cited by 28 publications

References 29 publications

Dimensional dependence of weak localization corrections and spin relaxation in quantum wires with Rashba spin-orbit coupling

Dimensional dependence of weak localization corrections and spin relaxation in quantum wires with Rashba spin-orbit coupling

Aharonov-Bohm oscillations and electron gas transitions in hexagonal core-shell nanowires with an axial magnetic field

Molecular Monolayer Nonvolatile Memory with Tunable Molecules

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