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Abstract: Solid He-4 is viewed as a nearly perfect Debye solid. Yet, recent calorimetrymeasurements by the PSU group J. Low Temp. Phys. 138, 853 2005 and Nature449, 1025 2007 indicate that at low temperatures the specific heat has bothcubic and linear contributions. These features appear in the same temperaturerange where measurements of the torsional oscillator period suggest asupersolid transition. We analyze the specific heat and compare the measuredwith the estimated entropy for a proposed supersolid transition with 1%superfluid fraction and find that the observed entropy is too small. We suggestthat the low-temperature linear term in the specific heat is due to a glassystate that develops at low temperatures and is caused by a distribution oftunneling systems in the crystal. We propose that dislocation related defectsproduce those tunneling systems. Further, we argue that the reported putativemass decoupling, that means an increase in the oscillator frequency, isconsistent with a glass-like transition. The glass scenario offers analternative interpretation of the torsional oscillator experiments in contrastto the supersolid scenario of nonclassical rotational inertia.



Autor: M.J. Graf, A.V. Balatsky, Z. Nussinov, I. Grigorenko, S.A. Trugman

Fuente: https://arxiv.org/







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