Exclusion of temperature fluctuations as the source of1fnoise in metal films

The measured coherence between the $\frac{1}{f}$ noise of two superimposed, thermally coupled but electrically insulated continuous gold films was found to be orders of magnitude smaller than it would be if this excess low-frequency noise were due to temperature fluctuations. Thus temperature fluctuations of either extrinsic or thermodynamic origin cannot generally be responsible for the $\frac{1}{f}$ noise observed in substrate-mounted metal films.