Temperature evolution of the phonon dynamics in the Kitaev spin liquid

Journal Article · Tue Jun 08 00:00:00 EDT 2021 · Physical Review. B

DOI:https://doi.org/10.1103/physrevb.103.214416· OSTI ID:1852479

Feng, Kexin ^[1]; Ye, Mengxing ^[2]; Perkins, Natalia B. ^[3]

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1. Univ. of Minnesota, Minneapolis, MN (United States); OSTI
2. Univ. of California, Santa Barbara, CA (United States)
3. Univ. of Minnesota, Minneapolis, MN (United States)

In this work, we present a study of the phonon dynamics in the honeycomb Kitaev spin model at finite temperatures. We show that the fractionalized spin excitations of the Kitaev spin liquid, the itinerant Majorana fermions, and static Z₂ fluxes have distinct effects on the phonon dynamics, which makes the phonon dynamics a promising tool for exploring the Kitaev spin liquid candidate materials. In particular, we focus on the signature of the fractionalized excitations in the thermodynamic behavior of the sound attenuation and the phonon Hall viscosity: the former describes the phonon decay into the fractionalized excitations, and the latter is the leading order time-reversal symmetry breaking effect on the acoustic phonon. We find that the angular dependence of the attenuation coefficient and its magnitude is modified by the thermal excitation of the Z₂ fluxes. The strength of this effect strongly depends on the relative magnitude of the sound velocity and the Fermi velocity characterizing the low-energy Majorana fermions. We also show that the Hall viscosity is strongly suppressed by the increase of the density of the Z₂ fluxes at finite temperatures. All these observations reflect the effects of the emergent disorder on the Majorana fermions introduced by the Z₂ fluxes. Our analysis is based on the complementary analytical calculations in the low-temperature zero-flux sector, and numerical calculations in the inhomogeneous flux sectors at intermediate and high temperatures with stratified Monte Carlo (strMC) method.

• Research Organization: Univ. of Minnesota, Minneapolis, MN (United States)
• Sponsoring Organization: Gordon and Betty Moore Foundation; National Science Foundation (NSF); USDOE Office of Science (SC), Basic Energy Sciences (BES)
• Grant/Contract Number: SC0018056
• OSTI ID: 1852479
• Journal Information: Physical Review. B, Journal Name: Physical Review. B Journal Issue: 21 Vol. 103; ISSN 2469-9950
• Publisher: American Physical Society (APS)
• Country of Publication: United States
• Language: English

Related Subjects

75 CONDENSED MATTER PHYSICS
SUPERCONDUCTIVITY AND SUPERFLUIDITY
Kitaev model
exact diagonalization
magnetism
materials science
phonons
physics
spin liquid