Thermal Relaxation in Metal Films Limited by Diffuson Lattice Excitations of Amorphous Substrates

Elmira M. Baeva, Nadezhda A. Titova, Louis Veyrat, Benjamin Sacépé, Alexander V. Semenov, Gregory N. Goltsman, Anna I. Kardakova, and Vadim. S. Khrapai
Phys. Rev. Applied 15, 054014 – Published 7 May 2021

Abstract

We examine the role of a silicon-based amorphous insulating substrate in the thermal relaxation in thin NbN, InOx, and Au/Ni films at temperatures above 5 K. The samples studied consist of metal bridges on an amorphous insulating layer lying on or suspended above a crystalline substrate. Noise thermometry is used to measure the electron temperature Te of the films as a function of Joule power per unit area P2D. In all samples, we observe a P2DTen dependence, with exponent n2, which is inconsistent with both electron-phonon coupling and Kapitza thermal resistance. In suspended samples, the functional dependence of P2D(Te) on the length of the amorphous insulating layer is consistent with the linear temperature dependence of the thermal conductivity, which is related to lattice excitations (diffusons) for a phonon mean free path shorter than the dominant phonon wavelength. Our findings are important for understanding the operation of devices embedded in amorphous dielectrics.

  • Figure
  • Received 18 January 2021
  • Revised 26 March 2021
  • Accepted 14 April 2021

DOI:https://doi.org/10.1103/PhysRevApplied.15.054014

© 2021 American Physical Society

Physics Subject Headings (PhySH)

Condensed Matter, Materials & Applied Physics

Authors & Affiliations

Elmira M. Baeva1,2, Nadezhda A. Titova1, Louis Veyrat3, Benjamin Sacépé3, Alexander V. Semenov1,4, Gregory N. Goltsman1,2, Anna I. Kardakova1,2,*, and Vadim. S. Khrapai2,5

  • 1Moscow Pedagogical State University, 29 Malaya Pirogovskaya Street, Moscow, Russia
  • 2National Research University Higher School of Economics, 20 Myasnitskaya Street, Moscow, Russia
  • 3Université Grenoble Alpes, CNRS, Grenoble INP, Institut Néel, 38000 Grenoble, France
  • 4Moscow Institute of Physics and Technology, 9 Institutsky Lane, Dolgoprudny, Russia
  • 5Institute of Solid State Physics, Russian Academy of Sciences, Chernogolovka, Russia

  • *akardakova@hse.ru

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Vol. 15, Iss. 5 — May 2021

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