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Ultrasound Attenuation in Sr$_2$RuO$_4$: an Angle-Resolved Study of the Superconducting Gap Function

C. Lupien·W. A. MacFarlane·Cyril Proust·Louis Taillefer·Z. Q. Mao·Y. Maeno
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Abstract

We present a study of the electronic ultrasound attenuation $α$ in the unconventional superconductor Sr$_2$RuO$_4$ . The power law behavior of $α$ at temperatures down to $T_c/30$ clearly indicates the presence of nodes in the gap. In the normal state, we find an enormous anisotropy of $α$ in the basal plane of the tetragonal structure. In the superconducting state, the temperature dependence of $α$ also exhibits significant anisotropy. We discuss these results in relation to possible gap functions.

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C. Lupien, W. A. MacFarlane, Cyril Proust, Louis Taillefer, Z. Q. Mao, Y. Maeno. 2001-04-23. Ultrasound Attenuation in Sr$_2$RuO$_4$: an Angle-Resolved Study of the Superconducting Gap Function. https://doi.org/10.1103/physrevlett.86.5986

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