2008/08/31 by M J Graf, M. J. Graf, A. V. Balatsky +7 · 1 citation
Chemistry · Materials Science · Physics and Astronomy · #Inorganic Fluorides and Related Compounds #Quantum, superfluid, helium dynamics #Solid-state spectroscopy and crystallography #cond-mat.dis-nn #cond-mat.mtrl-sci
paper · pdf · doi:10.1088/1742-6596/150/3/032025
published as Journal of Physics: Conference Series 150 (2009) 032025 (6 pages) · Presented at LT-25, Amsterdam 2008
arxiv created 2008/11/13 · openalex publication_date 2009/02/01 · arxiv updated 2011/04/08 · openalex created_date 2016/06/24 · openalex updated_date 2026/07/30
Solid 4 He is viewed as a nearly perfect Debye solid. Yet, recent calorimetry measurements by the PSU group (J. Low Temp. Phys. 138 , 853 (2005) and Nature 449 , 1025 (2007)) indicate that at low temperatures the specific heat has both cubic and linear contributions. These features appear in the same temperature range where measurements of the torsional oscillator period suggest a supersolid transition. We analyze the specific heat and compare the measured with the estimated entropy for a proposed supersolid transition with 1% superfluid fraction and find that the observed entropy is too small. We suggest that the low-temperature linear term in the specific heat is due to a glassy state that develops at low temperatures and is caused by a distribution of tunneling systems in the crystal. We propose that dislocation related defects produce those tunneling systems. Further, we argue that the reported putative mass decoupling, that means an increase in the oscillator frequency, is consistent with a glass-like transition. The glass scenario offers an alternative interpretation of the torsional oscillator experiments in contrast to the supersolid scenario of nonclassical rotational inertia.