Thermal conductivity of glassy materials and the "boson peak"W. Schirmacher
Argonne National Laboratory - 9700 S. Cass Avenue, Argonne, IL 60439, USA and Physik-Department E13, Technische Universität München James-Franck-Strasse 1, D-85747 Garching, Germany
received 15 August 2005; accepted in final form 17 January 2006
published online 3 February 2006
A theory for the anomalous vibrational and thermal properties of disordered solids based on the model assumption of randomly fluctuating transverse elastic constants is presented. Mean-field expressions for the vibrational density of states and the energy diffusivity are derived with field-theoretical techniques. As in previous approaches of this type the boson peak (enhancement of the low-frequency density of states) is explained as a result of the frozen-in disorder and compares well with the experimental findings. The plateau in the temperature variation of the thermal conductivity and the behavior beyond the plateau is shown to arise from the enhanced scattering in the boson peak regime and to be essentially a harmonic phenomenon.
63.50.+x - Vibrational states in disordered systems.
65.60.+a - Thermal properties of amorphous solids and glasses: heat capacity, thermal expansion, etc.
© EDP Sciences 2006