Microscopic study of 1/fnoise in metal nanobridges

Extensive studies of 1/f noise and its microscopic constituents have been conducted in clean metal nanobridges 3--40 nm wide. The resistance noise results from the fluctuation of metastable defects between discrete configurations; at low temperatures, activation energies, scattering cross-section changes, and attempt times are measured. Interactions between defects dominate the high-temperature noise signal, and are, in fact, required to produce a 1/f noise signal. The measured interaction strength is too large to be explained by a simple model of fluctuating elastic dipoles interacting through the lattice strain field. The analysis suggests that collective reconfigurations of regions of a ``defect glass'' are responsible both for the discrete fluctuations and the strong interaction energy. Implications for more disordered systems are discussed.