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arXiv · 1112.5998

$^4$He Crystal Quality and Rotational Response in a Transparent Torsional Oscillator

A. D. Fefferman·X. Rojas·A. Haziot·S. Balibar·J. T. West·M. H. W. Chan
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Abstract

We have studied natural purity $^{4}$He single crystals and polycrystals between 10 and 600 mK using a torsional oscillator with a 2 cm$^{3}$ rigid cell made of sapphire with a smooth geometry. As the temperature was lowered, we observed sample dependent but reproducible resonant frequency shifts that could be attributed to a supersolid fraction of order 0.1%. However, these shifts were observed with single crystals, not with polycrystals. Our results indicate that, in our case, the rotational anomaly of solid helium is more likely due to a change in stiffness than to supersolidity. This interpretation would presumably require gliding of dislocations in more directions than previously thought.

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A. D. Fefferman, X. Rojas, A. Haziot, S. Balibar, J. T. West, M. H. W. Chan. 2012-01-30. $^4$He Crystal Quality and Rotational Response in a Transparent Torsional Oscillator. https://doi.org/10.1103/physrevb.85.094103

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