Higher-order topology and corner triplon excitations in two-dimensional quantum spin-dimer models
arXiv:2104.12791 · doi:10.1103/PhysRevB.104.184403
Abstract
The concept of free fermion topology has been generalized to -dimensional phases that exhibit -dimensional boundary modes, such as zero-dimensional (0D) corner excitations. Motivated by recent extensions of these ideas to magnetic systems, we consider 2D quantum paramagnets formed by interacting spin dimers with dispersive triplet excitations. We propose two examples of such dimer models, where the spin-gapped bosonic triplon excitations are shown to host bands with nontrivial higher-order topology. We demonstrate this using real-space Bogoliubov--de Gennes calculations that reveal the existence of mid-bandgap corner triplon modes as a signature of higher-order bulk topology. We provide an understanding of the higher-order topology in these systems via a computation of bulk topological invariants as well as the construction of edge theories, and study their phase transitions as we tune parameters in the model Hamiltonians. We also discuss possible experimental approaches for detecting the emergent corner triplon modes.
20 pages, 4 figures
References in corpus (10)
- Electric Multipole Moments, Topological Multipole Moment Pumping, and Chiral Hinge States in Crystalline Insulators
- Bose-Einstein Condensation in Magnetic Insulators
- Evidence for deconfined quantum criticality in a two-dimensional Heisenberg model with four-spin interactions
- Dimensional reduction at a quantum critical point
- Hall effect of triplons in a dimerized quantum magnet
- Topological Bogoliubov excitations in inversion-symmetric systems of interacting bosons
- Chiral Hinge Magnons in Second-Order Topological Magnon Insulators
- A modified triplet-wave expansion method applied to the alternating Heisenberg chain
- Hinge Magnons from Non-collinear Magnetic Order in Honeycomb Antiferromagnet
- Fractional corner magnetization of collinear antiferromagnets