Abstract
The low-temperature properties of glass are distinct from those of crystals due to the presence of poorly understood low-energy excitations. The tunneling model proposes that these are atoms tunneling between nearby equilibria, forming tunneling two-level systems (TLSs). This model is rather successful, but it does not explain the remarkably universal value of the mechanical dissipation \(Q^{-1}\) near 1 K. The only known exceptions to this universality are the \(Q^{-1}\) of certain thin films of amorphous silicon, carbon and germanium. Recently, it was found that \(Q^{-1}\) of amorphous silicon (a-Si) films can be reduced by two orders of magnitude by increasing the temperature of the substrate during deposition. According to the tunneling model, the reduction in \(Q^{-1}\) at 1 K implies a reduction in \(P_{0}\gamma ^{2}\), where \(P_{0}\) is the density of TLSs and \(\gamma \) is their coupling to phonons. In this preliminary report, we demonstrate elastic measurements of a-Si films down to 20 mK. This will allow us, in future work, to determine whether \(P_{0}\) or \(\gamma \) is responsible for the reduction in \(Q^{-1}\) with deposition temperature.
Similar content being viewed by others
References
R.C. Zeller, R.O. Pohl, Phys. Rev. B 4(6), 2029 (1971). doi:10.1103/PhysRevB.4.2029
K. Agarwal, I. Martin, M.D. Lukin, E. Demler, Phys. Rev. B 87, 144201 (2013). doi:10.1103/PhysRevB.87.144201
D.C. Vural, A.J. Leggett, J. Non-Cryst, Solids 357, 3528 (2011). doi:10.1016/j.jnoncrysol.2011.06.035
P.W. Anderson, B.I. Halperin, C.M. Varma, Philos. Mag. 25, 1 (1972). doi:10.1080/14786437208229210
W.A. Phillips, J. Low Temp. Phys. 7, 351 (1972). doi:10.1007/BF00660072
R.O. Pohl, X. Liu, E. Thompson, Rev. Mod. Phys. 74(4), 991 (2002). doi:10.1103/RevModPhys.74.991
X. Liu, D.R. Queen, T.H. Metcalf, J.E. Karel, F. Hellman, Phys. Rev. Lett. 113, 025503 (2014). doi:10.1103/PhysRevLett.113.025503
S.F. Swallen, K.L. Kearns, M.K. Mapes, Y.S. Kim, R.J. McMahon, M.D. Ediger, T. Wu, L. Yu, S. Satija, Science 315(5810), 353 (2007)
W.A. Phillips, Rep. Prog. Phys. 50(12), 1657 (1987). doi:10.1088/0034-4885/50/12/003
A.D. Fefferman, R.O. Pohl, J.M. Parpia, Phys. Rev. B 82, 064302 (2010). doi:10.1103/PhysRevB.82.064302
X. Liu, S. Morse, J. Vignola, D. Photiadis, A. Sarkissian, M. Marcus, B. Houston, Appl. Phys. Lett. 78(10), 1346 (2001)
C.L. Spiel, R. Pohl, A.T. Zehnder, Rev. Sci. Instrum. 72, 1482 (2001)
X. Liu, T.H. Metcalf, J.T. Robinson, B.H. Houston, F. Scarpa, Nano Lett. 12(2), 1013 (2012)
J.T. Stockburger, M. Grifoni, M. Sassetti, Phys. Rev. B 51, 2835 (1995). doi:10.1103/PhysRevB.51.2835
A.D. Fefferman, R.O. Pohl, A.T. Zehnder, J.M. Parpia, Physical Review Letters 100(19), 195501 (2008). doi:10.1103/PhysRevLett.100.195501. URL http://link.aps.org/abstract/PRL/v100/e195501
A. Fefferman, The low temperature acoustic properties of amorphous silica and polycrystalline aluminum. Ph.D. thesis, Cornell University (2009). http://hdl.handle.net/1813/14013
Acknowledgments
We acknowledge support from the ERC CoG Grant ULT-NEMS No. 647917 and from the US Office of Naval Research.
Author information
Authors and Affiliations
Corresponding author
Rights and permissions
About this article
Cite this article
Fefferman, A., Maldonado, A., Collin, E. et al. Elastic Measurements of Amorphous Silicon Films at mK Temperatures. J Low Temp Phys 187, 654–660 (2017). https://doi.org/10.1007/s10909-016-1686-6
Received:
Accepted:
Published:
Issue Date:
DOI: https://doi.org/10.1007/s10909-016-1686-6