Maximized orbital and spin Kondo effects in a single-electron transistor

Karyn Le Hur, Pascal Simon, L. Borda

Research output: Contribution to journalArticle

28 Citations (Scopus)

Abstract

We investigate the charge fluctuations of a single-electron box (metallic grain) coupled to a lead via a smaller quantum dot in the Kondo regime. The most interesting aspect of this problem resides in the interplay between spin Kondo physics stemming from the screening of the spin of the small dot and orbital Kondo physics emerging when charging states of the grain with (charge) Q=0 and Q=e are almost degenerate. Combining Wilson's numerical renormalization-group method with perturbative scaling approaches we push forward our previous work [K. Le Hur and P. Simon, Phys. Rev. B 67, 201308R (2003)]. We emphasize that, for symmetric and slightly asymmetric barriers, the strong entanglement of charge and spin flip events in this setup inevitably results in a nontrivial stable SU(4) Kondo fixed point near the degeneracy points of the grain. By analogy with a small dot sandwiched between two leads, the ground state is Fermi-liquid-like, which considerably smears out the Coulomb staircase behavior and prevents the Matveev logarithmic singularity from arising. Most notably, the associated Kondo temperature TK SU(4) might be raised compared to that in conductance experiments through a small quantum dot (∼ 1 K), which makes the observation of our predictions a priori accessible. We discuss the robustness of the SU(4) correlated state against the inclusion of an external magnetic field, a deviation from the degeneracy points, particle-hole symmetry in the small dot, and asymmetric tunnel junctions and comment on the different crossovers.

Original languageEnglish
Article number045326
Pages (from-to)453261-4532616
Number of pages4079356
JournalPhysical Review B - Condensed Matter and Materials Physics
Volume69
Issue number4
Publication statusPublished - Jan 2004

Fingerprint

Kondo effect
Single electron transistors
single electron transistors
orbitals
Semiconductor quantum dots
Physics
quantum dots
Fermi liquids
smear
physics
Tunnel junctions
stairways
renormalization group methods
tunnel junctions
Ground state
charging
boxes
emerging
crossovers
Screening

ASJC Scopus subject areas

  • Condensed Matter Physics

Cite this

Maximized orbital and spin Kondo effects in a single-electron transistor. / Le Hur, Karyn; Simon, Pascal; Borda, L.

In: Physical Review B - Condensed Matter and Materials Physics, Vol. 69, No. 4, 045326, 01.2004, p. 453261-4532616.

Research output: Contribution to journalArticle

@article{5575f603c9ff48c89ade9fa0b9014310,
title = "Maximized orbital and spin Kondo effects in a single-electron transistor",
abstract = "We investigate the charge fluctuations of a single-electron box (metallic grain) coupled to a lead via a smaller quantum dot in the Kondo regime. The most interesting aspect of this problem resides in the interplay between spin Kondo physics stemming from the screening of the spin of the small dot and orbital Kondo physics emerging when charging states of the grain with (charge) Q=0 and Q=e are almost degenerate. Combining Wilson's numerical renormalization-group method with perturbative scaling approaches we push forward our previous work [K. Le Hur and P. Simon, Phys. Rev. B 67, 201308R (2003)]. We emphasize that, for symmetric and slightly asymmetric barriers, the strong entanglement of charge and spin flip events in this setup inevitably results in a nontrivial stable SU(4) Kondo fixed point near the degeneracy points of the grain. By analogy with a small dot sandwiched between two leads, the ground state is Fermi-liquid-like, which considerably smears out the Coulomb staircase behavior and prevents the Matveev logarithmic singularity from arising. Most notably, the associated Kondo temperature TK SU(4) might be raised compared to that in conductance experiments through a small quantum dot (∼ 1 K), which makes the observation of our predictions a priori accessible. We discuss the robustness of the SU(4) correlated state against the inclusion of an external magnetic field, a deviation from the degeneracy points, particle-hole symmetry in the small dot, and asymmetric tunnel junctions and comment on the different crossovers.",
author = "{Le Hur}, Karyn and Pascal Simon and L. Borda",
year = "2004",
month = "1",
language = "English",
volume = "69",
pages = "453261--4532616",
journal = "Physical Review B-Condensed Matter",
issn = "0163-1829",
publisher = "American Physical Society",
number = "4",

}

TY - JOUR

T1 - Maximized orbital and spin Kondo effects in a single-electron transistor

AU - Le Hur, Karyn

AU - Simon, Pascal

AU - Borda, L.

PY - 2004/1

Y1 - 2004/1

N2 - We investigate the charge fluctuations of a single-electron box (metallic grain) coupled to a lead via a smaller quantum dot in the Kondo regime. The most interesting aspect of this problem resides in the interplay between spin Kondo physics stemming from the screening of the spin of the small dot and orbital Kondo physics emerging when charging states of the grain with (charge) Q=0 and Q=e are almost degenerate. Combining Wilson's numerical renormalization-group method with perturbative scaling approaches we push forward our previous work [K. Le Hur and P. Simon, Phys. Rev. B 67, 201308R (2003)]. We emphasize that, for symmetric and slightly asymmetric barriers, the strong entanglement of charge and spin flip events in this setup inevitably results in a nontrivial stable SU(4) Kondo fixed point near the degeneracy points of the grain. By analogy with a small dot sandwiched between two leads, the ground state is Fermi-liquid-like, which considerably smears out the Coulomb staircase behavior and prevents the Matveev logarithmic singularity from arising. Most notably, the associated Kondo temperature TK SU(4) might be raised compared to that in conductance experiments through a small quantum dot (∼ 1 K), which makes the observation of our predictions a priori accessible. We discuss the robustness of the SU(4) correlated state against the inclusion of an external magnetic field, a deviation from the degeneracy points, particle-hole symmetry in the small dot, and asymmetric tunnel junctions and comment on the different crossovers.

AB - We investigate the charge fluctuations of a single-electron box (metallic grain) coupled to a lead via a smaller quantum dot in the Kondo regime. The most interesting aspect of this problem resides in the interplay between spin Kondo physics stemming from the screening of the spin of the small dot and orbital Kondo physics emerging when charging states of the grain with (charge) Q=0 and Q=e are almost degenerate. Combining Wilson's numerical renormalization-group method with perturbative scaling approaches we push forward our previous work [K. Le Hur and P. Simon, Phys. Rev. B 67, 201308R (2003)]. We emphasize that, for symmetric and slightly asymmetric barriers, the strong entanglement of charge and spin flip events in this setup inevitably results in a nontrivial stable SU(4) Kondo fixed point near the degeneracy points of the grain. By analogy with a small dot sandwiched between two leads, the ground state is Fermi-liquid-like, which considerably smears out the Coulomb staircase behavior and prevents the Matveev logarithmic singularity from arising. Most notably, the associated Kondo temperature TK SU(4) might be raised compared to that in conductance experiments through a small quantum dot (∼ 1 K), which makes the observation of our predictions a priori accessible. We discuss the robustness of the SU(4) correlated state against the inclusion of an external magnetic field, a deviation from the degeneracy points, particle-hole symmetry in the small dot, and asymmetric tunnel junctions and comment on the different crossovers.

UR - http://www.scopus.com/inward/record.url?scp=1542344038&partnerID=8YFLogxK

UR - http://www.scopus.com/inward/citedby.url?scp=1542344038&partnerID=8YFLogxK

M3 - Article

AN - SCOPUS:1542344038

VL - 69

SP - 453261

EP - 4532616

JO - Physical Review B-Condensed Matter

JF - Physical Review B-Condensed Matter

SN - 0163-1829

IS - 4

M1 - 045326

ER -