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Title: Quantum Point Contacts: A Naturally-Formed Single-Spin System.

Abstract

Abstract not provided.

Authors:
;  [1]; ; ; ; ;
  1. Sandia National Laboratories, Livermore, CA
Publication Date:
Research Org.:
Sandia National Lab. (SNL-CA), Livermore, CA (United States); Sandia National Lab. (SNL-NM), Albuquerque, NM (United States)
Sponsoring Org.:
USDOE National Nuclear Security Administration (NNSA)
OSTI Identifier:
1137311
Report Number(s):
SAND2007-1952J
523774
DOE Contract Number:
DE-AC04-94AL85000
Resource Type:
Journal Article
Resource Relation:
Journal Name: Nature; Related Information: Proposed for publication in Nature.
Country of Publication:
United States
Language:
English

Citation Formats

Reno, John Louis, Yoon, Paul Y., Mourokh, L., Morimoto, T., Aoki, N., Ochiai, Y., and Bird, J. P. Quantum Point Contacts: A Naturally-Formed Single-Spin System.. United States: N. p., 2007. Web.
Reno, John Louis, Yoon, Paul Y., Mourokh, L., Morimoto, T., Aoki, N., Ochiai, Y., & Bird, J. P. Quantum Point Contacts: A Naturally-Formed Single-Spin System.. United States.
Reno, John Louis, Yoon, Paul Y., Mourokh, L., Morimoto, T., Aoki, N., Ochiai, Y., and Bird, J. P. Thu . "Quantum Point Contacts: A Naturally-Formed Single-Spin System.". United States. doi:.
@article{osti_1137311,
title = {Quantum Point Contacts: A Naturally-Formed Single-Spin System.},
author = {Reno, John Louis and Yoon, Paul Y. and Mourokh, L. and Morimoto, T. and Aoki, N. and Ochiai, Y. and Bird, J. P.},
abstractNote = {Abstract not provided.},
doi = {},
journal = {Nature},
number = ,
volume = ,
place = {United States},
year = {Thu Mar 01 00:00:00 EST 2007},
month = {Thu Mar 01 00:00:00 EST 2007}
}
  • We introduce a spin-interference device that comprises a quantum ring (QR) with three embedded quantum point contacts (QPCs) and study theoretically its spin transport properties in the presence of Rashba spin-orbit interaction. Two of the QPCs conform the lead-to-ring junctions while a third one is placed symmetrically in the upper arm of the QR. Using an appropriate scattering model for the QPCs and the S-matrix scattering approach, we analyze the role of the QPCs on the Aharonov-Bohm (AB) and Aharonov-Casher (AC) conductance oscillations of the QR-device. Exact formulas are obtained for the spin-resolved conductances of the QR-device as a functionmore » of the confinement of the QPCs and the AB/AC phases. Conditions for the appearance of resonances and anti-resonances in the spin-conductance are derived and discussed. We predict very distinctive variations of the QR-conductance oscillations not seen in previous QR proposals. In particular, we find that the interference pattern in the QR can be manipulated to a large extend by varying electrically the lead-to-ring topological parameters. The latter can be used to modulate the AB and AC phases by applying gate voltage only. We have shown also that the conductance oscillations exhibits a crossover to well-defined resonances as the lateral QPC confinement strength is increased, mapping the eigenenergies of the QR. In addition, unique features of the conductance arise by varying the aperture of the upper-arm QPC and the Rashba spin-orbit coupling. Our results may be of relevance for promising spin-orbitronics devices based on quantum interference mechanisms.« less
  • No abstract prepared.
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  • A novel technique has been used to determine the effective diffusion coefficients for 1,1,2-trichloroethane (TCE), a nonreacting tracer, in biofilms growing on the external surface of a silicone rubber membrane tube during degradation of 1,2-dichloroethane (DCE) by Xanthobacter autotrophicus GJ10 and monochlorobenzene (MCB) by Pseudomonas JS150. Experiments were carried out in a single tube extractive membrane bioreactor (STEMB), whose configuration makes it possible to measure the transmembrane flux of substrates. A video imaging technique (VIT) was employed for in situ biofilm thickness measurement and recording. Diffusion coefficients of TCE in the biofilms and TCE mass transfer coefficients in the liquidmore » films adjacent to the biofilms were determined simultaneously using a resistances-in-series diffusion model. It was found that the flux and overall mass transfer coefficient of TCE decrease with increasing biofilm thickness, showing the importance of biofilm diffusion on the mass transfer process. Similar fluxes were observed for the nonreacting tracer (TCE) and the reactive substrates (MCB or DCE), suggesting that membrane-attached biofilm systems can be rate controlled primarily by substrate diffusion. The TCE diffusion coefficient in the JS150 biofilm appeared to be dependent on biofilm thickness, decreasing markedly for biofilm thicknesses of >1 mm. The values of the TCE diffusion coefficients in the JS150 biofilms <1-mm thick are approximately twice those in water and fall to around 30% of the water value for biofilms >1-mm thick.« less
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