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 similar to0.7(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.