Determination of the diffusion constant in disordered mesoscopic Au rings from the temperature dependence of the current

A simple calculation to determine the diffusion constant D for electrons in disorder mesoscopic Au rings from the temperature dependence of the current obtained by Chandrasekhar et al. (1991) [1] gives larger D than the diffusion constant D′ obtained from Einstein's relation via resistance measurements. In addition, the curve-fitting function employed by them does not agree well with the temperature-dependent data below 10 mK. Using a more precise calculation based on the quasi-particle picture, we show that the discrepancy between the fitting function and the experimental data below 10 mK is reduced and that a newly obtained D is close to D′. The method proposed here is very simple to determine the diffusion constant in a small closed loop via the curve-fitting of the temperature-dependent data, which needs no resistance measurements for the use of Einstein's relation.