Open AccessTHEORY OF ULTRASONIC ABSORPTION WITH INFRARED DIVERGENCE IN GLASSES AT LOW TEMPERATURES
Author(s) -
Guoliang Wang,
Dai Pei-Ying,
Fan Xi-Qing,
Jiang Wang-Ye,
Liu Fu-Sui
Publication year - 1987
Publication title -
wuli xuebao
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.199
H-Index - 47
ISSN - 1000-3290
DOI - 10.7498/aps.36.1441
Subject(s) - absorption (acoustics) , divergence (linguistics) , materials science , infrared , diffusion , condensed matter physics , nonlinear system , microscopic theory , excitation , physics , thermodynamics , quantum mechanics , optics , philosophy , linguistics
The nonlinear behavior of ultrasonic absorption in glasses below 2 K is analysed by combining the two-level systems model and the infrared divergence theory. A modification of the existing tunneling two-level model of Jackie et al. is given. The Bloch equations are used as the macroscopic equations of the "magnetization" and all quantities in the equations as en-sebmble averages rather than a state expectation value. With this modification, and the defect state as a pseudo-spin in the local fluctuation field, the relation between the angle diffusion of the spin and the temperature at low temperatures is deduced. The theoretical absorption curve obtained is consistent with the experimental data. The observed T-0.7 rule of the resonance absorption under weak excitation and the proportional relation of the saturated absorption to ω2 are also explained.