ダイマー反強磁性体におけるトポロジカルトリプロンバンド

抄録

A topological insulator is a material that has gapped bulk and conducting edge states due to the difference in topological characteristics between the bulk and the edge. The concept of topologically insulating state has been extended to bosonic quasiparticles, such as magnons and triplons in solids. We demonstrate that triplons construct bands with topologically protected edge states in the spin-1/2 dimerized antiferromagnet Ba₂CuSi₂O₆Cl₂. A bond-alternation of interdimer couplings leads to complex hopping amplitudes of triplons, which leads to non-trivial topology of the bands. A triplon hopping model realized in Ba₂CuSi₂O₆Cl₂ is interpreted as a pseudo-one-dimensional variant of Su-Schrieffer-Heeger (SSH) model, indicating that topologically protected edge states are induced by a bipartite nature of the lattice.