A tunable Kondo effect of quantum dots

Science

Volumn 281, Issue 5376, 1998, Pages 540-544

  Cronenwett, Sara M ^a,b   Oosterkamp, Tjerk H ^a   Kouwenhoven, Leo P ^a  

^a DELFT UNIVERSITY OF TECHNOLOGY   (Netherlands)

^b STANFORD UNIVERSITY   (United States)

Author keywords

[No Author keywords available]

Indexed keywords

ARTICLE; CONDUCTANCE; ELECTRON; ENERGY; MAGNETIC FIELD; PHYSICS; PRIORITY JOURNAL; QUANTUM THEORY; TEMPERATURE DEPENDENCE;

EID: 0032563237     PISSN: 00368075     EISSN: None     Source Type: Journal    
DOI: 10.1126/science.281.5376.540     Document Type: Article

References (27)

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11. J. König, J. Schmid, H. Schoeller, G. Schön, Phys. Rev. B 54, 16820 (1996); for further references, see H. Schoeller, in Mesoscopic Electron Transport, Proceedings of a NATO Advanced Study Institute, L. L. Sohn, L. P. Kouwenhoven, G. Schön, Eds. (Kluwer, Dordrecht, Netherlands, 1997), ser. E, vol. 345, pp. 291-330.
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16. In measurements of the evolution of the CB peaks versus B, we observe pairing in the motion between adjacent peaks. This indicates spin-degenerate filling of the energy states, in contrast to the results of D. R. Stewart et al. [Science 278, 1784 (1997)], who reported non-spin-degenerate filling of the energy states.
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18. The two quantum dots form the double dot structure discussed in detail by N. C. van der Vaart et al. [Phys. Rev. Lett. 74, 4702 (1995)]. Each dot was measured independently by biasing only the gate voltages that define a single dot.
19. base ≈ 45 mK, was measured from CB peak widths in the weak tunneling regime.
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21. The presence of more than one state in our dots is expected to enhance the Kondo temperature. For an analysis of multiple-level effects, see T. Inoshita et al., Phys. Rev. B 48, 14725 (1993); T. Inoshita, Y. Kuramoto, H. Sakaki, Superlattices Microstruct. 22, 75 (1997); T. Pohjola et al., Europhys. Lett. 40, 189 (1997).
22. The presence of more than one state in our dots is expected to enhance the Kondo temperature. For an analysis of multiple-level effects, see T. Inoshita et al., Phys. Rev. B 48, 14725 (1993); T. Inoshita, Y. Kuramoto, H. Sakaki, Superlattices Microstruct. 22, 75 (1997); T. Pohjola et al., Europhys. Lett. 40, 189 (1997).
23. The presence of more than one state in our dots is expected to enhance the Kondo temperature. For an analysis of multiple-level effects, see T. Inoshita et al., Phys. Rev. B 48, 14725 (1993); T. Inoshita, Y. Kuramoto, H. Sakaki, Superlattices Microstruct. 22, 75 (1997); T. Pohjola et al., Europhys. Lett. 40, 189 (1997).
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25. The dl/dV minimum of valley 4 resembles the form predicted by J. König, H. Schoeller, and G. Schön [Phys. Rev. Lett. 76, 1715 (1996)] for a quantum dot with N = even.
26. Our data fit well to the theoretical predictions when we use the g factor for bulk GaAs, g = -0.44, whereas the g factor in the 2DEG of a typical GaAs/ AlGaAs heterostructure has been experimentally determined to be less than in the bulk by M. Dobers, K. v. Klitzing, and C. Weimann [Phys. Rev. B 38, 5453 (1988)].
27. We thank R. Aguado, B. Broer, L. I. Glazman, S. F. Godijn, K. K. Likharev, C. M. Marcus, J. E. Mooij, and N. C. van der Vaart for help and discussions and Philips Laboratories and C. T. Foxon for providing the heterostructure. Supported by the Dutch Foundation for Fundamental Research on Matter (FOM), the Royal Netherlands Academy of Arts and Sciences (L.P.K.), and the NSF under grant DMR-945805 (S.M.C.).