Evidence for Charging Effects in CdTe/CdMgTe Quantum Point Contacts

TL;DR

This study demonstrates charging effects in CdTe/CdMgTe quantum point contacts, revealing the formation of a weakly bound state and spontaneous open dot, which influence conductance behavior at low temperatures.

Contribution

It provides experimental evidence for charging effects and spontaneous dot formation in CdTe quantum point contacts, a novel observation in this material system.

Findings

Weakly bound state inside quantum constrictions due to charging effects

Replacement of conductance plateaus by quasi-periodic resonances

Observation of weaker conductance peaks below 1 K

Abstract

Here we report on fabrication and low temperature magnetotransport measurements of quantum point contacts patterned from a novel two-dimensional electron system - CdTe/CdMgTe modulation doped heterostructure. From the temperature and bias dependence we ascribe the reported data to evidence for a weakly bound state which is naturally formed inside a CdTe quantum constrictions due to charging effects. We argue that the spontaneous introduction of an open dot is responsible for the replacement of flat conductance plateaus by quasi-periodic resonances with amplitude less than 2e^{2}/h, as found in our system. Additionally, below 1 K a pattern of weaker conductance peaks, superimposed upon wider resonances, is also observed.