Phonon dynamics in the site-disordered Kitaev spin liquid

Journal Article · 23 September 2024 · Physical Review. B

DOI: https://doi.org/10.1103/physrevb.110.104425 · OSTI ID:2448002

Dantas, Vitor  ^[1]; Kao, Wen-Han  ^[2]; Perkins, Natalia B.  ^[2]

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1. University of Minnesota, Minneapolis, MN (United States); University of Minnesota, Minneapolis
2. University of Minnesota, Minneapolis, MN (United States)

The Kitaev honeycomb model provides a paradigmatic example of an exactly solvable quantum spin liquid (QSL), where spins fractionalize into itinerant Majorana fermions coupled to a static background of $$\mathbb{Z}_{2}$$ gauge fluxes. This model has attracted significant interest due to its potential experimental realization in spin-orbit Mott insulators like $$\alpha$$-RuCl$$_3$$. Among various experimental techniques, ultrasound measurements of sound attenuation have emerged as a promising approach to detect spin fractionalization in these materials. However, deviations from the ideal Kitaev model, often due to disorder, introduce localized modes that dominate the low-energy physics. To investigate these effects, we calculate the sound attenuation coefficient in the site-disordered Kitaev honeycomb model under an applied magnetic field that breaks time-reversal symmetry. Our analysis reveals that quasilocalized modes from quasivacancies impact the phonon self-energy, yet the sound attenuation coefficient maintains its sixfold symmetry and linear temperature dependence at low temperatures, even with disorder. Here, this robustness underscores sound attenuation's reliability as a probe for spin fractionalization. Furthermore, we show that this linear behavior persists under an external field and in the random-flux sector, highlighting the persistent influence of fractionalized excitations, despite disorder.

• Research Organization: University of Minnesota, Minneapolis, MN (United States)
• Sponsoring Organization: USDOE Office of Science (SC), Basic Energy Sciences (BES)
• Grant/Contract Number: SC0018056
• OSTI ID: 2448002
• Journal Information: Physical Review. B, Journal Name: Physical Review. B Journal Issue: 10 Vol. 110; ISSN 2469-9950
• Publisher: American Physical Society (APS)Copyright Statement
• Country of Publication: United States
• Language: English