Publication

Odd and even Kondo effects from emergent localization in quantum point contacts

Iqbal, M. J., Levy, R., Koop, E. J., Dekker, J. B., de Jong, J. P., van der Velde, J. H. M., Reuter, D., Wieck, A. D., Aguado, R., Meir, Y. & van der Wal, C. H., 5-Sep-2013, In : Nature. 501, 7465, p. 79-+ 6 p.

Research output: Contribution to journalArticleAcademicpeer-review

APA

Iqbal, M. J., Levy, R., Koop, E. J., Dekker, J. B., de Jong, J. P., van der Velde, J. H. M., ... van der Wal, C. H. (2013). Odd and even Kondo effects from emergent localization in quantum point contacts. Nature, 501(7465), 79-+. https://doi.org/10.1038/nature12491

Author

Iqbal, M. J. ; Levy, Roi ; Koop, E. J. ; Dekker, J. B. ; de Jong, J. P. ; van der Velde, J. H. M. ; Reuter, D. ; Wieck, A. D. ; Aguado, Ramon ; Meir, Yigal ; van der Wal, C. H. / Odd and even Kondo effects from emergent localization in quantum point contacts. In: Nature. 2013 ; Vol. 501, No. 7465. pp. 79-+.

Harvard

Iqbal, MJ, Levy, R, Koop, EJ, Dekker, JB, de Jong, JP, van der Velde, JHM, Reuter, D, Wieck, AD, Aguado, R, Meir, Y & van der Wal, CH 2013, 'Odd and even Kondo effects from emergent localization in quantum point contacts', Nature, vol. 501, no. 7465, pp. 79-+. https://doi.org/10.1038/nature12491

Standard

Odd and even Kondo effects from emergent localization in quantum point contacts. / Iqbal, M. J.; Levy, Roi; Koop, E. J.; Dekker, J. B.; de Jong, J. P.; van der Velde, J. H. M.; Reuter, D.; Wieck, A. D.; Aguado, Ramon; Meir, Yigal; van der Wal, C. H.

In: Nature, Vol. 501, No. 7465, 05.09.2013, p. 79-+.

Research output: Contribution to journalArticleAcademicpeer-review

Vancouver

Iqbal MJ, Levy R, Koop EJ, Dekker JB, de Jong JP, van der Velde JHM et al. Odd and even Kondo effects from emergent localization in quantum point contacts. Nature. 2013 Sep 5;501(7465):79-+. https://doi.org/10.1038/nature12491


BibTeX

@article{11457ddd61754fabba8d8c7723fed37a,
title = "Odd and even Kondo effects from emergent localization in quantum point contacts",
abstract = "A quantum point contact (QPC) is a basic nanometre-scale electronic device: a short and narrow transport channel between two electron reservoirs. In clean channels, electron transport is ballistic and the conductance is then quantized as a function of channel width(1,2) with plateaux at integer multiples of 2e(2)/h (where e is the electron charge and h is Planck's constant). This can be understood in a picture where the electron states are propagating waves, without the need to account for electron-electron interactions. Quantized conductance could thus be the signature of ultimate control over nanoscale electron transport. However, even studies with the cleanest QPCs generically show significant anomalies in the quantized conductance traces, and there is consensus that these result from electron many-body effects(3,4). Despite extensive experimental and theoretical studies(4-11), understanding these anomalies is an open problem. Here we report that the many-body effects have their origin in one or more spontaneously localized states that emerge from Friedel oscillations in the electron charge density within the QPC channel. These localized states will have electron spins associated with them, and the Kondo effect-related to electron transport through such localized electron spins-contributes to the formation of the many-body state(5-7). We present evidence for such localization, with Kondo effects of odd or even character, directly reflecting the parity of the number of localized states; the evidence is obtained from experiments with length-tunable QPCs that show a periodic modulation of the many-body properties with Kondo signatures that alternate between odd and even Kondo effects. Our results are of importance for assessing the role of QPCs in more complex hybrid devices(12,13) and for proposals for spintronic and quantum information applications(14,15). In addition, our results show that tunable QPCs offer a versatile platform for investigating many-body effects in nanoscale systems, with the ability to probe such physics at the level of a single site.",
keywords = "DIMENSIONAL ELECTRON-GAS, QUANTIZED CONDUCTANCE, DOTS, TRANSPORT, SIGNATURES, DEVICES",
author = "Iqbal, {M. J.} and Roi Levy and Koop, {E. J.} and Dekker, {J. B.} and {de Jong}, {J. P.} and {van der Velde}, {J. H. M.} and D. Reuter and Wieck, {A. D.} and Ramon Aguado and Yigal Meir and {van der Wal}, {C. H.}",
year = "2013",
month = "9",
day = "5",
doi = "10.1038/nature12491",
language = "English",
volume = "501",
pages = "79--+",
journal = "Nature",
issn = "0028-0836",
publisher = "Nature Publishing Group",
number = "7465",

}

RIS

TY - JOUR

T1 - Odd and even Kondo effects from emergent localization in quantum point contacts

AU - Iqbal, M. J.

AU - Levy, Roi

AU - Koop, E. J.

AU - Dekker, J. B.

AU - de Jong, J. P.

AU - van der Velde, J. H. M.

AU - Reuter, D.

AU - Wieck, A. D.

AU - Aguado, Ramon

AU - Meir, Yigal

AU - van der Wal, C. H.

PY - 2013/9/5

Y1 - 2013/9/5

N2 - A quantum point contact (QPC) is a basic nanometre-scale electronic device: a short and narrow transport channel between two electron reservoirs. In clean channels, electron transport is ballistic and the conductance is then quantized as a function of channel width(1,2) with plateaux at integer multiples of 2e(2)/h (where e is the electron charge and h is Planck's constant). This can be understood in a picture where the electron states are propagating waves, without the need to account for electron-electron interactions. Quantized conductance could thus be the signature of ultimate control over nanoscale electron transport. However, even studies with the cleanest QPCs generically show significant anomalies in the quantized conductance traces, and there is consensus that these result from electron many-body effects(3,4). Despite extensive experimental and theoretical studies(4-11), understanding these anomalies is an open problem. Here we report that the many-body effects have their origin in one or more spontaneously localized states that emerge from Friedel oscillations in the electron charge density within the QPC channel. These localized states will have electron spins associated with them, and the Kondo effect-related to electron transport through such localized electron spins-contributes to the formation of the many-body state(5-7). We present evidence for such localization, with Kondo effects of odd or even character, directly reflecting the parity of the number of localized states; the evidence is obtained from experiments with length-tunable QPCs that show a periodic modulation of the many-body properties with Kondo signatures that alternate between odd and even Kondo effects. Our results are of importance for assessing the role of QPCs in more complex hybrid devices(12,13) and for proposals for spintronic and quantum information applications(14,15). In addition, our results show that tunable QPCs offer a versatile platform for investigating many-body effects in nanoscale systems, with the ability to probe such physics at the level of a single site.

AB - A quantum point contact (QPC) is a basic nanometre-scale electronic device: a short and narrow transport channel between two electron reservoirs. In clean channels, electron transport is ballistic and the conductance is then quantized as a function of channel width(1,2) with plateaux at integer multiples of 2e(2)/h (where e is the electron charge and h is Planck's constant). This can be understood in a picture where the electron states are propagating waves, without the need to account for electron-electron interactions. Quantized conductance could thus be the signature of ultimate control over nanoscale electron transport. However, even studies with the cleanest QPCs generically show significant anomalies in the quantized conductance traces, and there is consensus that these result from electron many-body effects(3,4). Despite extensive experimental and theoretical studies(4-11), understanding these anomalies is an open problem. Here we report that the many-body effects have their origin in one or more spontaneously localized states that emerge from Friedel oscillations in the electron charge density within the QPC channel. These localized states will have electron spins associated with them, and the Kondo effect-related to electron transport through such localized electron spins-contributes to the formation of the many-body state(5-7). We present evidence for such localization, with Kondo effects of odd or even character, directly reflecting the parity of the number of localized states; the evidence is obtained from experiments with length-tunable QPCs that show a periodic modulation of the many-body properties with Kondo signatures that alternate between odd and even Kondo effects. Our results are of importance for assessing the role of QPCs in more complex hybrid devices(12,13) and for proposals for spintronic and quantum information applications(14,15). In addition, our results show that tunable QPCs offer a versatile platform for investigating many-body effects in nanoscale systems, with the ability to probe such physics at the level of a single site.

KW - DIMENSIONAL ELECTRON-GAS

KW - QUANTIZED CONDUCTANCE

KW - DOTS

KW - TRANSPORT

KW - SIGNATURES

KW - DEVICES

U2 - 10.1038/nature12491

DO - 10.1038/nature12491

M3 - Article

VL - 501

SP - 79-+

JO - Nature

JF - Nature

SN - 0028-0836

IS - 7465

ER -

ID: 5946498