Date : Jun. 16 (Fri.), 2023, 16:00～17:00
Place : A615 and On Zoom (Hybrid)
Speaker : Dr. Kiyu Fukui
Affiliation : Department of Applied Physics, The University of Tokyo
Title : Feasibility study of quantum spin liquid in extensions of the Kitaev model
Abstract：
The Kitaev model provides us with a rare example of exact quantum
spin liquid (QSL) states in more than one dimension. While it is very important
to explore new platforms for realizing the Kitaev QSL theoretically, extensions
of the model make it no longer solvable and numerical calculations are
challenging. Here we address the feasibility of the Kitaev QSL for three
extensions of the model, by using the pseudofermion functional renormalization
group method.
The first one is the extension to higher-spin systems [1]. We
clarify the ground-state phase diagrams of the spin-S Kitaev-Heisenberg
model systematically by changing the ratio between the Kitaev and Heisenberg
interactions and the length of spin S. We find that the Kitaev QSL
regions remain stable for S < 2, whereas the regions are quickly
shrunk while increasing S.
The second one is the extension to three-dimensional (3D) systems [2].
Studying the Kitaev-Heisenberg model defined on a 3D hyperhoneycomb lattice, we
show that the ground-state phase diagram is similar to the two-dimensional
honeycomb case. Our results respect the four-sublattice symmetry inherent in
the model, which was violated in the previous study.
The last one is for ultracold polar molecules trapped in an optical
lattice [3]. We study a model proposed as an implementation of the Kitaev-type
interactions, and clarify that the ground state is magnetically ordered. We also
unravel how the Kitaev QSL is destabilized by the long-range interactions
originating from the dipole interactions between polar molecules.[1] K. Fukui, Y. Kato, J. Nasu, and Y. Motome, Phys. Rev. B 106, 174416 (2022).
[2] K. Fukui, Y. Kato, and Y. Motome, J. Phys. Soc. Jpn. 92, 064708 (2023).
[3] K. Fukui, Y. Kato, J. Nasu, and Y. Motome, Phys. Rev. B 106, 014419 (2022)..
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