Abstract
The nonlinear nature of the acoustic response of metallic glasses at very low temperatures, which has defied a satisfactory theoretical description until now, is explained in terms of the tunneling model by the intrinsically nonlinear response of two-level systems to an external force. Recent advances in the systematic theoretical treatment of this nonlinear response including the effect of Ohmic ...
Abstract
The nonlinear nature of the acoustic response of metallic glasses at very low temperatures, which has defied a satisfactory theoretical description until now, is explained in terms of the tunneling model by the intrinsically nonlinear response of two-level systems to an external force. Recent advances in the systematic theoretical treatment of this nonlinear response including the effect of Ohmic dissipation are used in a detailed model, with special emphasis on vibrating-reed experiments. The apparent contradiction between the assumptions of the tunneling model and experimental results is naturally reconciled when a valid theory is substituted for the linear response approximation. Our results are in quantitative agreement with experimental data for both sound velocity and acoustic absorption.
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