Chennai Mathematical Institute


Physics Seminar
Date/Time: 27th January, 2023, 11 AM
Venue: Lecture Hall 802
Systematic generation of the dynamical higher-order topological insulator and superconductor phases in three dimensions

Tanay Nag
Uppsala University, Sweden.


In recent times, the higher-order topological (HOT) phases, harboring boundary modes of lower dimensions than their usual ones, have been proposed with unconventional bulk-boundary correspondence. We have come up with a general framework to construct the HOT insulator [1] and superconductor (with s-wave superconductivity) [2] phases, preserving unitary chiral and anti-unitary particle-hole symmetries, with appropriate Wilson-Dirac masses. We periodically kick these mass terms to generate the ladder of HOT phases that are only protected by the anti-unitary particle-hole symmetry while the static system remains in the lower-order topological or trivial phase [1,2]. We characterize these static and dynamic HOT phases with suitable topological invariants namely, quadrupolar moment, octupolar moment, and Wannier spectra. Apart from zero energy regular HOT modes, we also find finite energy anomalous HOT modes [3,4]. find At the end, we connect it to the recent experimental findings to highlight the relevance of this field.

[1] Hierarchy of higher-order Floquet topological phases in three dimensions, T. Nag, V. Juricic, B. Roy, Phys. Rev. B 103, 115308 (2021).

[2] Hierarchy of higher-order topological superconductors in three dimensions, A. K. Ghosh, T. Nag, A. Saha, Phys. Rev. B 104, 134508 (2021).

[3] Systematic generation of the cascade of anomalous dynamical first and higher-order modes in Floquet topological insulators, A. K. Ghosh, T. Nag, A. Saha, Phys. Rev. B 105, 115418 (2022).

[4] Dynamical construction of Quadrupolar and Octupolar topological superconductors, A. K. Ghosh, T. Nag, A. Saha, Phys. Rev. B 105, 155406