Evidence for interplay between pseudogap and orthorhombicity in underdoped YBa$_2$Cu$_3$O$_y$ from ultrasound measurement

YBa2Cu3Oy from ultrasound measurements M. Frachet, ∗ Daniel J. Campbell, Anne Missiaen, S. Benhabib, Francis Laliberté, B. Borgnic, T. Loew, J. Porras, S. Nakata, B. Keimer, M. Le Tacon, Cyril Proust, I. Paul, † and David LeBoeuf ‡ LNCMI-EMFL, CNRS UPR3228, Univ. Grenoble Alpes, Univ. Toulouse, Univ. Toulouse 3, INSA-T, Grenoble and Toulouse, France Max-Planck-Institut für Festkörperforschung, Heisenbergstrasse 1, Stuttgart, D-70569, Germany Institute for Quantum Materials and Technologies, Karlsruhe Institute of Technology, D-76344, Eggenstein-Leopoldshafen, Germany Laboratoire Matériaux et Phénomènes Quantiques, CNRS, Université de Paris, F-75205 Paris, France (Dated: June 7, 2021)