LIMITS OF UNIVERSALITY IN DISORDERED CONDUCTORS

A straightforward microscopic approach is developed to evaluate the distribution of transmission eigenvalues for a disordered phase-coherent conductor. In the diffusive limit, the calculation generalizes the result of random matrix theory that the universal distribution is not dependent on the shape of the conductor. Extended defects such as tunnel barriers and grain boundaries were shown to break the universality. If the resistance of the tunnel barrier comprises half of the total resistance, a drastic change of the distribution is found. This indicates an analog of localization transition.