Dissipative superfluid mass flux through solid 4He

The thermo-mechanical effect in superfluid helium is used to create an initial chemical potential difference, $\Delta \mu_0$, across a solid $^4$He sample. This $\Delta \mu_0$ causes a flow of helium atoms from one reservoir filled with superfluid helium, through a sample cell filled with solid helium, to another superfluid-filled reservoir until chemical potential equilibrium is restored. The solid helium sample is separated from each of the reservoirs by Vycor rods that allow only the superfluid component to flow. With an improved technique, measurements of the flow, $F$, at several fixed solid helium temperatures, $T$, have been made as function of $\Delta \mu$ in the pressure range 25.5 - 26.1 bar. And, measurements of $F$ have been made as a function of temperature in the range $180 < T < 545$~mK for several fixed values of $\Delta \mu$. The temperature dependence of the flow above $100$~mK shows a reduction of the flux with an increase in temperature that is well described by $F = F_0^*[1 - a\exp(-E/T)]$. The non-linear functional dependence $F \sim (\Delta \mu)^b$, with $b < 0.5$ independent of temperature but dependent on pressure, documents in some detail the dissipative nature of the flow and suggests that this system demonstrates Luttinger liquid-like one-dimensional behavior. The mechanism that causes this flow behavior is not certain, but is consistent with superflow on the cores of edge dislocations.Comment: 11 pages, 14 figure

Mass flux characteristics in solid 4He for T> 100 mK: Evidence for Bosonic Luttinger Liquid behavior

At pressure $\sim$ 25.7 bar the flux, $F$, carried by solid \4he for $T >$ 100 mK depends on the net chemical potential difference between two reservoirs in series with the solid, $\Delta \mu$, and obeys $F \sim (\Delta \mu)^b$, where $b \approx 0.3$ is independent of temperature. At fixed $\Delta \mu$ the temperature dependence of the flux, $F$, can be adequately represented by $F \sim - \ln(T/\tau)$, $\tau \approx 0.6$ K, for $0.1 \leq T \leq 0.5$ K. A single function $F = F_0(\Delta \mu)^b\ln(T/\tau)$ fits all of the available data sets in the range 25.6 - 25.8 bar reasonably well. We suggest that the mass flux in solid \4he for $T > 100$ mK may have a Luttinger liquid-like behavior in this bosonic system.Comment: 4 pages, 5 figure

Effect of Crystal Quality on HCP-BCC Phase Transition in Solid 4He

The kinetics of HCP-BCC structure phase transition is studied by precise pressure measurement technique in 4He crystals of different quality. An anomalous pressure behavior in bad quality crystals under constant volume conditions is detected just after HCP-BCC structure phase transition. A sharp pressure drop of 0.2 bar was observed at constant temperature. The subsequent pressure kinetics is a non-monotonic temperature function. The effect observed can be explained if we suppose that microscopic liquid droplets appear on the HCP-BCC interphase region in bad quality crystals. After the interphase region disappearance, these droplets are crystallized with pressure reduction. It is shown that this effect is absent in high quality thermal-treated crystals.Comment: 4 pages, 4 figure

Mass flux characteristics in solid 4He for T \u3e 100 mK: Evidence for Bosonic Luttinger Liquid behavior

At a pressure of ~25.7 bar, the flux F carried by solid 4_He for T \u3e 100 mK depends on the net chemical potential difference between two reservoirs in series with the solid, ∆ u, and obeys F ~ (∆µ) b, where b ≈ 0.3 is independent of temperature. At fixed ∆µ the temperature dependence of the flux F can be adequately represented by F ~ - In(T/t), t ≈ 0.6 K, for 0.1 ≤ T ≤ 0.5 K. A single function F = F_0 (∆µ)b In(T/t) fits all of the available data sets in the range 25.6-25.8 bar reasonably well. We suggest that the mass flux in solid 4_He for T \u3e 100 mK may have a Luttinger liquidlike behavior in this bosonic system

Universal temperature dependence, flux extinction and the role of 3He impurities in superfluid mass transport through solid 4He

The mass flux, F, carried by as-grown solid 4_He in the range 25.6-26.3 bar rises with falling temperature, and at a concentration-dependent temperature, T_d, the flux decreases sharply within a few mK. We study F as a function of 3_He impurity concentration, χ. We find that T_(d )is an increasing function of increasing χ. At temperatures above T_d the flux has a universal temperature dependence and the flux terminates in a narrow window near a characteristic temperature T_h ≈ 625 mK, which is independent of χ