A `Superglass' State in Solid ^4He
Abstract
We study the relaxation dynamics of both the resonance frequency f(T) and the dissipation rate D(T)=Q-1(T) of a torsional oscillator (TO) containing solid ^4He. Abruptly at the temperature T* characteristic of the proposed supersolid phase, the relaxation times within f(T) and D(T) begin to increase precipitously together. Moreover, for all T<T*, relaxation processes in both D(T) and a component of f(T) exhibit a synchronized ultra-slow evolution towards equilibrium and strong thermal hysteresis. We demonstrate that, while reminiscent of glassy dynamics, these phenomena are quantitatively inconsistent with a simple freeze-out transition because the variation in f is far too large. We conclude that, if solid ^4He exhibits a superfluid component, this system represents a new form of quantum matter -- a complex supersolid in which a crystalline excitation exhibiting glassy dynamics controls the superfluid phase stiffness.
- Publication:
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APS March Meeting Abstracts
- Pub Date:
- March 2009
- Bibcode:
- 2009APS..MARP16007H