2025/04/23 by Lahiri, Srijata, Bhattacharyya, Kuntal, Basu, Saurabh · 1 citation
#FOS: Physical sciences #Mesoscale and Nanoscale Physics (cond-mat.mes-hall)
paper · doi:10.48550/arxiv.2504.16674
In this work, a thorough exploration has been carried out to unravel the role of electron-phonon interaction (EPI) in a Bernevig-Hughes-Zhang (BHZ) quantum spin Hall (QSH) insulator subjected to a time-periodic step drive. It is observed that upon inclusion of the EPI, the system demonstrates emergent Floquet QSH (FQSH) phases and several topological phase transitions therein, mediated solely by the interaction strength. Quite intriguingly, the emergence of topological zero (π) modes in the bulk that remains otherwise gapless in the vicinity of the π (zero) energy sector is observed, thus serving as a prime candidate of robust topology in gapless systems. With other invariants being found to be deficient in characterizing such coexistent phases, a spectral localizer (SL) is employed, which distinctly ascertains the nature of the (zero or π) edge modes. Following the SL prescription, a real-space Chern marker computed by us further provides support to such gapless Floquet topological scenario. Our results can be realized in advanced optical setups that may underscore the importance of EPI-induced Floquet features.