Abstract
We investigate the amplitude of mesoscopic fluctuations of the differential conductance of a metallic wire at arbitrary bias voltage . For noninteracting electrons, the variance increases with . The asymptotic large- behavior is (where is the Thouless energy), in agreement with the earlier prediction by Larkin and Khmelnitskii. We find, however, that this asymptotics has a very small numerical prefactor and sets in at very large only, which strongly complicates its experimental observation. This high-voltage behavior is preceded by a crossover regime, , where the conductance variance increases by a factor as compared to its value in the regime of universal conductance fluctuations (i.e., at ). We further analyze the effect of dephasing due to the electron-electron scattering on at high voltages. With the Coulomb interaction taken into account, the amplitude of conductance fluctuations becomes a nonmonotonic function of . Specifically, drops as for voltages , where is the dimensionless conductance. In this regime, the conductance fluctuations are dominated by quantum-coherent regions of the wire adjacent to the reservoirs.
- Received 2 June 2004
DOI:https://doi.org/10.1103/PhysRevB.70.235315
©2004 American Physical Society