[GS_C_MS] Hund-Driven Topological Semimetal in a Ruthenate System
ABSTRACT
The interplay between strong electron correlations and topology has been an active area of research in condensed matter physics and quantum materials, suggesting the possibility of discovering new physical phenomena or topological phases. However, previous studies on strongly correlated topological materials have primarily focused on Mott physics due to strong Coulomb interactions, leaving Hund exchange coupling largely unexplored. In this talk, we introduce a scenario in which Hund coupling drives the emergence of a novel topological phase. We begin with a PT-symmetry-protected nodal line semimetal in the absence of spin-orbit coupling (SOC) and then introduce SOC, which deteriorates the nodal structure and results in a compensated semimetal. Despite the gap opening, the parity of the occupied states and the Z2 topological invariants are preserved, leading to a topological compensated semimetal phase. Furthermore, we demonstrate that Hund coupling can compete with SOC through orbital-selective self-energy effects arising from the Hund coupling. This competition can give rise to a novel, strongly correlated nodal semimetal. Using DFT+DMFT calculations, we discuss the possibility of realizing this Hund-driven topological semimetal phase in a ruthenate system.