Domain wall states in high spin topological insulators

We extend the concept of topological insulators to include a class of higher spin systems, with potential applications in ultracold atomic gases. Recent developments in understanding particle with higher spin have enriched knowledge of unique topological phases of matter [1,2]. While in conventional solid-state physics the electrons inherently have a spin of 1/2, the interplay between spin and orbital angular momentum results in an effective total angular momentum of J=3/2 [1]. Furthermore, ultracold atomic gas systems exhibit intrinsic high spin characteristics. Prior theoretical investigation has explored the topological insulating phases in two-dimensional spin-orbit-coupled spin 3/2 atomic gases [2].

In this work, we focus on the effect of an in-plane magnetic field on these topological phases. We have found that at the boundary between opposing in-plane magnetic fields, degenerate domain-wall states emerge, extending the concept of the Jackiw-Rebbi bound states in quantum spin Hall insulator to systems with high spins systems [3]. In the presentation, we will provide insights into the topological properties of these high spin domain-wall sates.

[1] T. Kawakami, T. Okamura, S. Kobayashi, and M. Sato, Phys. Rev. X 8, 041026, (2018).

[2] I. Kuzmenko, T. Kuzmenko, Y. Avishai, and M. Sato, Phys. Rev. B 98, 165139, (2018).

[3] X. L. Qi, T. L. Hughes, S. C. Zhang Nat. Phys. 4, 273 (2008).