Low-temperature fate of the 0.7 structure in a point contact: a Kondo-like correlated state in an open system.
Besides the usual conductance plateaus at multiples of 2e(2)/h, quantum point contacts typically show an extra plateau at approximately 0.7(2e(2)/h), believed to arise from electron-electron interactions that prohibit the two spin channels from being simultaneously occupied. We present evidence that the disappearance of the 0.7 structure at very low temperature signals the formation of a Kondo-like correlated spin state. Evidence includes a zero-bias conductance peak that splits in a parallel field, scaling of conductance to a modified Kondo form, and consistency between peak width and the Kondo temperature.
Cronenwett
S M
SM
Department of Physics, Harvard University, Cambridge, Massachusetts 02138, USA.
Lynch
H J
HJ
Goldhaber-Gordon
D
D
Kouwenhoven
L P
LP
Marcus
C M
CM
Hirose
K
K
Wingreen
N S
NS
Umansky
V
V