Two-stage Kondo effect in a quantum dot at a high magnetic field.
We report a strong Kondo effect (Kondo temperature approximately 4 K) at high magnetic field in a selective area growth semiconductor quantum dot. The Kondo effect is ascribed to a singlet-triplet transition in the ground state of the dot. At the transition, the low-temperature conductance approaches the unitary limit. Away from the transition, for low bias voltages and temperatures, the conductance is sharply reduced. The observed behavior is compared to predictions for a two-stage Kondo effect in quantum dots coupled to single-channel leads.
van der Wiel
W G
WG
Department of Applied Physics, DIMES, and ERATO Mesoscopic Correlation Project, Delft University of Technology, P.O. Box 5046, 2600 GA Delft, The Netherlands.
De Franceschi
S
S
Elzerman
J M
JM
Tarucha
S
S
Kouwenhoven
L P
LP
Motohisa
J
J
Nakajima
F
F
Fukui
T
T