Weakly open quantum dots: Magnetotransport spectroscopy and zero-field resistance peaks

The role of the environment on the observation of specific transport properties is discussed for open ballistic quantum dots. The saturation of phase-breaking at temperatures below 1 K is found to be mediated by lead coupling, which is found to affect the nature of the observed zero-field resistance peak. This can generally be attributed to the lead-induced modification of the available density of states in the dot, which is related to the magnetoconductance spectrum. Simulations of the magnetoconductance spectrum demonstrate that averaging the spectrum produces widely varying zero-field-resistance peaks in the same system. The exact nature of the environmental coupling in quantum dots is required to study the non-universal character of transport in these systems.