Mass Superflux in Solid Helium: the Role of ${}^3$He Impurities

Abstract

Below $\sim 630$~mK, the \4he atom mass flux, $F$, that passes through a cell filled with solid hcp \4he in the pressure range 25.6 - 26.4~bar, rises with falling temperature and at a temperature $T_d$ the flux drops sharply. The flux above $T_d$ has characteristics that are consistent with the presence of a bosonic Luttinger liquid. We study $F$ as a function of ${}^3$He concentration, $\chi =0.17-220$~ppm, to explore the effect of ${}^3$He impurities on the mass flux. We find that the strong reduction of the flux is a sharp transition, typically complete within a few mK and a few hundred seconds. Modest concentration-dependent hysteresis is present. We find that $T_d$ is an increasing function of $\chi$ and the $T_d(\chi )$ dependence differs somewhat from the predictions for bulk phase separation for $T_{ps}$ \emph{vs.} $\chi$. We conclude that ${}^3$He plays an important role in the flux extinction. The dependence of $F$ on the solid helium density is also studied. We find that $F$ is sample-dependent, but that the temperature dependence of $F$ above $T_d$ is universal; data for all samples scales and collapses to a universal temperature dependence, independent of ${}^3$He concentration or sample history. The universal behavior extrapolates to zero flux in the general vicinity of $T_h\approx 630$~mK. With increases in temperature, it is possible that a thermally activated process contributes to the degradation of the flux. The possibility of the role of disorder and the resulting phase slips as quantum defects on one-dimensional conducting pathways is discussed.

13 pages, 19 figures

References in corpus (8)

• Luttinger Liquid in the Core of Screw Dislocation in Helium-4
• Observation of Unusual Mass Transport in Solid hcp 4He
• Helium-4 Luttinger liquids in nanopores
• Interacting bosons in one dimension and Luttinger liquid theory
• Binding of a 3He impurity to a screw dislocation in solid 4He
• Dissipative superfluid mass flux through solid 4He
• NMR study of the dynamics of 3He impurities in the proposed supersolid state of solid 4He
• Characterization of the Surface of Moving solid 4He

Cited by in corpus (3)

• Multiple Mode Torsional Oscillator Studies and Evidence for Supersolidity in Bulk 4He
• Plasticity induced superclimb in solid Helium-4: Direct and inverse effects
• Anomalously Small Excitation Gaps as a Precursor of Dislocation Core Superfluidity in Solid Helium-4