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Condensed Matter Seminars

ics Condensed Matter
Wednesday, October 18, 2006
4:00 PM
Physics Building, Room 204
Note special date.
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Ricardo Schwarz [Host: Vittorio Celli]
Los Alamos National Laboratory
"Low Energy Vibrational Excitations in Metallic Glasses"
The specific heat and elastic constants of metallic glasses show anomalies not seen in crystals. These anomalies result from low-energy vibrational excitations in the glass. We have measured the low-temperature heat capacity, the elastic constants, and the phonon density of states of both glassy and single-phase crystalline Pd40Cu40P20. The specific heats of both alloys, plotted as CP/T3 vs. T, show different humps (commonly known as "Boson Peaks"). The elastic constants of the crystal and glass have different T-dependence: the shear modulus of the glass varies as C'(T) = C'(0)[1 - AT], whereas that of the crystal varies as C'(T) = C'(0)[1 - BT2 - DT4]. This suite of low-temperature measurements enabled us to identify the low-energy vibrational excitations responsible for these anomalies

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