Modification of electron-phonon coupling by micromachining and suspension

Kavli Affiliate: Michael Roukes

| First 5 Authors: Olli-Pentti Saira, Matthew H. Matheny, Libin Wang, Jukka Pekola, Michael Roukes

| Summary:

Weak electron-phonon interaction in metals at low temperatures forms the
basis of operation for cryogenic hot-electron bolometers and calorimeters.
Standard power laws, describing the heat flow in the majority of experiments,
have been identified and derived theoretically. However, a full picture
encompassing experimentally relevant effects such as reduced dimensionality,
material interfaces, and disorder is in its infancy, and has not been tested
extensively. Here, we study the electron-phonon heat flow in a thin gold film
on a SiO${}_2$ platform below 100 mK using supercurrent thermometry. We find
the power law exponent to be modified from 5.1 to 4.6 as the platform is
micromachined and released from its substrate. We attribute this change to a
modified phonon spectrum. The findings are compared to past experiments and
theoretical models.

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