概要

　We study magnetoelastic interactions by means of ultrasound experiments in α-RuCl₃ — a prototypical material for the Kitaev spin model on the honeycomb lattice, with a possible spin-liquid state featuring Majorana fermions and Z₂-flux excitations [1]. A comprehensive data analysis above the magnetically ordered state provides strong evidence of phonon scattering by Majorana fermions. This scattering depends sensitively on the value of the phonon velocities relative to the characteristic velocity of the low-energy fermionic excitations describing the spin dynamics of the underlying Kitaev magnet. Furthermore, we investigate the effects of hydrostatic pressure on α-RuCl₃ and reveal significant modifications of the acoustic properties and the H-T phase diagram of this material [2]. Above 0.28 GPa, the sound attenuation becomes nearly temperature-independent, suggesting a shift in the phonon scattering regime dominated by Majorana fermions.  We demonstrate the potential of phonon dynamics as a promising probe for uncovering fractionalized excitations in α-RuCl₃.

References
[1]. A. Hauspurg, S. Zherlitsyn, T. Helm, V. Felea, J. Wosnitza, V. Tsurkan, K.-Y. Choi, S.-H. Do, Mengxing Ye, W. Brenig, and N. B. Perkins, Phys. Rev. B 109, 144415 (2024).
[2]. A. Hauspurg, S. Singh, T. Yanagisawa, V. Tsurkan, J. Wosnitza, W. Brenig, N. B. Perkins, and S. Zherlitsyn, in preparation.

問合先：柳澤達也
tatsuya@phys.sci.hokudai.ac.jp