Evidence for a Superglass State in Solid 4He

B. Hunt, E. Pratt, V. Gadagkar, M. Yamashita, A. V. Balatsky, Seamus Davis

Research output: Contribution to journalArticlepeer-review

115 Citations (Scopus)


Although solid helium-4 (He-4) may be a supersolid, it also exhibits many phenomena unexpected in that context. We studied relaxation dynamics in the resonance frequency f(T) and dissipation D(T) of a torsional oscillator containing solid He-4. With the appearance of the "supersolid" state, the relaxation times within f(T) and D(T) began to increase rapidly together. More importantly, the relaxation processes in both D(T) and a component of f(T) exhibited a complex synchronized ultraslow evolution toward equilibrium. Analysis using a generalized rotational susceptibility revealed that, while exhibiting these apparently glassy dynamics, the phenomena were quantitatively inconsistent with a simple excitation freeze-out transition because the variation in f was far too large. One possibility is that amorphous solid He-4 represents a new form of supersolid in which dynamical excitations within the solid control the superfluid phase stiffness.

Original languageEnglish
Pages (from-to)632-636
Number of pages5
Issue number5927
Publication statusPublished - 1 May 2009


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