Regensburg 2016 – wissenschaftliches Programm
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MM: Fachverband Metall- und Materialphysik
MM 4: Liquid and Amorphous Metals I: Glassy dynamics
MM 4.4: Vortrag
Montag, 7. März 2016, 11:00–11:15, H52
Thermodynamic Properties of Zr- and Au-based Bulk Metallic Glasses Low Temperatures — •Andreas Reifenberger1, Mahmoud Abdel-Hafiez2, Andreas Fleischmann1, Andreas Reiser1, and Christian Enss1 — 1Kirchhoff-Institut für Physik, Universität Heidelberg, INF 227, 69120 Heidelberg — 2Physikalisches Institut, Goethe-Universität Frankfurt, Max-von-Laue-Str. 1, 60438 Frankfurt am Main
The origin of low temperature excitations in bulk metallic glasses is still an open question. We report on measurements of both low-temperature specific heat Cp and thermal conductivity κ of two model glasses based on Au and Zr (Au-BMG and Zr-BMG, respectively) in the temperature range from 1K to room temperature. We find pronounced low temperature anomalies in the phononic specific heat Cph, which are attributed to localized harmonic vibration modes. These Einstein modes act as additional scattering centers as can be seen in a plateau region in the thermal conductivity data. Furthermore, we derive the phonon mean free path l = 3 κ / (CV v), finding an overdamped region for temperatures higher than the corresponding Einstein energies. It is noteworthy that the mean free path in the overdamped region is comparable to phonon wavelengths corresponding to the found Einstein energies.