Gapless topological media
Together with Timo Hyart we studied the fate of the quantum spin Hall (QSH) topological transition in presence of interactions. For sufficiently strong ones we found that the gapless point is avoided by spontaneously breaking time-reversal symmetry. I plan to build on this insight and study the topological phase transitions in different symmetry classes, as well as Dirac and nodal line topological materials in presence of interactions.
The phase diagram of the QSH system with interactions is below. It shows three phases: trivial and topological insulators and insulator with spontaneously broken timer-reversal symmetry.
(c) APS, figure adopted from Phys. Rev. Lett. 112, 176403 (2014)