メーリングリストのみなさま，
物性研の川島です．下記のように理論セミナーを開催します．会場＋zoomのハイブリッドです．ご参加を歓迎します．
Dear Colleagues,
The following Theory Seminar (online and onsite) will be held on 16
Jun, Friday.
You are very welcome to attend.
For online participation, please pre-register at the link below.
forms.gle/g6PzWp1oAGoGHttV9
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Date: Jun. 16 (Fri.), 2023
Time: 16:00-17:00
Place: Seminar Room 5 (A615), 6th Floor, ISSP/ Online (Zoom)
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)..
Contact : Naoki Kawashima
e-mail: kawashima@issp.u-tokyo.ac.jp
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