Change Of Coupling Mechanism In The Low-Frequency Noise Of RuO2-Glass Films

Measurements of noise spectra in the range 1K - 300K show that spectral and temperature slopes obey Dutta Dimon and Horn equation [Phys. Rev. Lett. 43, 646 (1979)] only in the range T > 10 K. Below this temperature a gap of constant width opens between noise exponent calculated from the spectral slope and from temperature dependence of noise magnitude. This gap occurs due to the change of noise coupling mechanism that takes place at [approximate] 10 K. At higher temperatures this coupling is temperature independent, possibly modulation of the rates for tunneling transitions. At lower temperatures coupling becomes temperature dependent. It is shown that data agree quantitatively with the concept that noise sources modulate energies of thermally activated process.