Localization and capacitance fluctuations in disordered Au nanojunctions

Nanojunctions, containing atomic-scale gold contacts between strongly disordered leads, exhibit different transport properties at room temperature and at low temperature. At room temperature, the nanojunctions exhibit conductance quantization effects. At low temperatures, the contacts exhibit Coulomb blockade. We show that the differences between the room-temperature and low-temperature properties arise from the localization of electronic states in the leads. The charging energy and capacitance of the nanojunctions exhibit strong fluctuations, with applied magnetic field at low temperature, as predicted theoretically.