Scattering of acoustic phonons by rare earth substitutional atoms in yttrium aluminum garnets |
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Authors: | S N Ivanov E N Khazanov T Paszkiewicz A V Taranov M Wilczyński |
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Institution: | (1) Institute of Radioengineering and Electronics, Russian Academy of Sciences, ul. Mokhovaya 11, GSP-3, 103907 Moscow, Russia;(2) Institute of Theoretical Physics, University of Wrocław, Pl. M. Borna 9, PL-50-204 Wrocław, Poland |
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Abstract: | The diffusive maxima of phonon signals, and in particular their arrival timest
m are examined for a number of solid solutions of rare earth atoms in yttrium aluminum garnets. The phonon pulses are generated
by metallic films of the characteristic lengthl
h heated by current pulses to the temperatureT
h slightly higher than the ambient temperatureT. The injected phonons travel in wafers of the thicknessL
z. They are scattered by substitutional atoms of rare earth occupying the yttrium dodecahedral sites, rare earth and yttrium
atoms occupying the aluminum octahedral sites and by another lattice imperfections generated in the process of sample growing.
The qualitative analysis based on our exact formula for the diffusion coefficientD allows us to extract the contribution of rare earth atoms substituting the Y atoms toD. Considering the dependence oft
m/L
z
2
on the temperature and the ratiol
h/Lz we conclude thatD∼T
h
−4
and that the energy of phonons forming the diffusive maxima ranges from 3.2k
BTH to 4.2k
BTH, which is in reasonable agreement with the existing estimates. |
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Keywords: | 63 20 M 66 70 05 60 |
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