Resistance noise in amorphous Ni-Zr: Hydrogen diffusion and universal conductance fluctuations

Resistance fluctuations with a power spectrum of approximately 1/f have been studied in amorphous thin films of Ni30Zr70 and Ni50Zr50 in the temperature range 4<T<350 K. The primary noise-generating source was found to be hydrogen contamination with concentrations up to roughly 30 at. %. Exceptionally large peaks in the spectral density versus T corresponding to short-range hopping of hydrogen atoms were found between 90 and 200 K. The rms resistivity change due to short-range hopping of a hydrogen atom was found to be larger than the average resistivity increase per atom, indicating the importance of the random local environment. Below 50 K the noise increased with decreasing temperature and was reduced by magnetic fields, indicating a universal conductance-fluctuation-coupling mechanism.