ISSN:
1573-7357
Quelle:
Springer Online Journal Archives 1860-2000
Thema:
Physik
Notizen:
Abstract Both the real and imaginary parts of the transverse acoustic impedance of normal liquid3He have been measured at excitation frequencies of 10 and 30 MHz, fluid pressures from 0.7 to 27 bar, and temperatures from 3 mK to 1 K. The impedance is obtained from the changes in resonance frequency and Q of a quartz crystal, which is electrically driven to oscillate in a thickness shear mode while immersed in liquid3He. These results are compared with the predictions of Fermi liquid theory, which takes into account two contributions to the impedance: (1) incoherent single-quasiparticle excitations, and (2) the excitation of the collective transverse sound mode. At 0.7 bar, our measurements of the impedance are in agreement with the predictions of Fermi liquid theory and imply that the symmetric Fermi liquid parameterF 2=1.25±0.4 ifF 1=6.3. At higher pressures, we also observe agreement in the region ωτ〈0.3, where ω is the excitation frequency and τ is the quasiparticle scattering time. However, above 8 bar in the zero-sound regime (ωτ≳1), the impedance is observed to be frequency dependent, at constant ωτ. This frequency dependence cannot be explained within the present framework of Fermi liquid theory.
Materialart:
Digitale Medien
URL:
http://dx.doi.org/10.1007/BF00654490
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