On the Novel Superfluidity in the Second Layer of ${}^4$He on Graphite

Abstract

Evidence for a new type of superfluid phase in second-layer ${}^4$He on graphite has been obtained from simultaneous measurements of torsional-oscillator response and heat-capacity on exactly the same sample down to 30 mK, which resolve substrate-related uncertainties in the previous studies. The new phase hosts both superfluidity and enhanced viscoelasticity, and is stable over a finite density interval, strongly supporting the proposed superfluid liquid-crystal hypothesis. A random-Josephson-network analysis shows that the widely reported log-$T$ dependence of the superfluid density is likely due to substrate imperfections.

Manuscript combined with Supplementary Materials; 15 pages, 12 figures

References in corpus (7)

• Theory of Intertwined Orders in High Temperature Superconductors
• Phase diagram of 4He adsorbed on graphite
• Sub-unity superfluid fraction of a supersolid from self-induced Josephson effect
• Spatially Modulated Superfluid State in Two-Dimensional ${}^4$He Films
• Superfluid and supersolid phases of 4He on the second layer of graphite
• Second layer crystalline phase of helium films on graphite
• Transverse Quantum Superfluids