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Condensed Matter Seminars

ics Condensed Matter
Wednesday, October 18, 2006
4:00 PM
Physics Building, Room 204
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Ricardo Schwarz [Host: Vittorio Celli]
Los Alamos National Laboratory
"Low Energy Vibrational Excitations in Metallic Glasses"
ABSTRACT:
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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