Reply to Comment on Phys. Rev. Lett. 127, 176601 (2021) by Lee and Yang
arXiv:2305.15666 · doi:10.1103/PhysRevLett.130.219702
Abstract
In this Reply, we respond to the comments in Phys. Rev. Lett. 130, 219702 (2023) on our Phys. Rev. Lett. 127, 176601 (2021) ''Coulomb instabilities of a three-Dimensional higher-order topological insulator". We show the surface gap given in Phys. Rev. Lett. 130, 219701 (2023) is different from the expression derived by using the well-accepted approach and becomes divergent and singular at lower energies, thus is not suitable for depicting the phase transition from the 2nd-order to 1st-order topological insulator. We further show that a correct surface gap can describe the phase transition if the RG scheme treats the bulk gap as starting point. We justify our criteria in Phys. Rev. Lett. 127, 176601 (2021) for both the transitions from 2nd-order topological insulator to 1st-order topological insulator and normal insulator.
3 pages,1 figure. A long version with the detailed calculations