Fractionalized Excitations in Quantum Spin Liquids

by Kang Wang (TU München)

Thursday 5 Dec 2024, 11:00 → 12:00 Europe/Zurich

WBBC/111

Quantum spin liquids (QSLs) are long-range entangled states of matter characterized by
fractionalized degrees of freedom. The direct experimental detection of these fractionalized
particles remains a substantial challenge. Based on the single-mode approximation iPEPS
algorithm, we investigated the spin dynamics in the Kitaev honeycomb model under an out-of-
plane magnetic  eld, a system that exhibits a transition from a gapped chiral spin-liquid (CSL)
phase to a debated gapless phase. In the  rst part of the talk, I will identify experimentally
detectable signatures of fractionalized excitations in the chiral spin-liquid phase [1], where the
ux and Majorana fermion degrees of freedom are separable. In the second segment, I will
address the gapless excitations under moderate  eld. We proposed a theoretical mechanism
for the emergence of the gapless phase, where the proliferating ?- uxes create an emergent
Majorana metallic state with a `Fermi surface' at zero energy [2,3].
[1] Fractionalization Signatures in the Dynamics of Quantum Spin Liquids
Kang Wang, Shi Feng, Penghao Zhu, Runze Chi, Hai-Jun Liao, N. Trivedi and Tao Xiang,
arXiv:2403.12141.
[2] Emergent Majorana Metal in a Chiral Quantum Spin Liquid
Penghao Zhu, Shi Feng, Kang Wang, Tao Xiang and N. Trivedi, arXiv:2405.12278.
[3] Anyon dynamics in  eld-driven phases of the anisotropic Kitaev model
Shi Feng, A. Agarwala, S. Bhattacharjee and N. Trivedi, Phys. Rev. B 108, 035149 (2023).