Zero Sound Attenuation near the Quantum Limit in Normal Liquid 3He close to the Superfluid Transition

TL;DR

This study investigates zero sound attenuation in normal liquid helium-3 near the superfluid transition, testing Landau's quantum limit predictions across various frequencies and temperatures close to Tc.

Contribution

The paper provides detailed experimental measurements of zero sound attenuation near Tc, comparing results with Landau's theoretical predictions in the quantum limit.

Findings

Attenuation data agrees with Landau's prediction in the quantum limit

Zero sound attenuation shows temperature dependence near Tc

Calibration confirms consistency with previous measurements

Abstract

The zero sound attenuation of normal liquid 3He has been studied over a range of temperatures from slightly above the superfluid transition temperature, Tc, to approximately 10 mK at the constant pressures of 1 bar and 5 bar. Using longitudinal LiNbO3 transducers, operating both on and off resonance, the experiment was performed at 15 discrete frequencies located in several broadband frequency windows, including 16 - 25 MHz, 60 - 70 MHz, and 105 - 111 MHz. The results are compared to Landau's prediction for the attenuation of zero sound in the quantum limit, k_{B}T << \hbar \omega << k_{B}T_{F}, where \alpha_{0}(P,T,\omega) = \alpha^{\prime}(P) T^{2} {1+(\hbar \omega/2 \pi k_{B}T)^{2}}. Calibration of the received zero sound signals was performed by measuring the temperature dependence of the first sound attenuation from 30 mK to 800 mK at those same frequencies and pressures. The data are compared to previous results.