Work

d ‐Wave Fermi Surface Instability in the Nematic Phase of Two Monolayer FeSe/SrTiO 3

Year: 2025

Type: article

Abstract: Nematicity, where electrons break rotational symmetry while preserving translational symmetry, is ubiquitous in strongly correlated quantum matters, including high‐ T c cuprates and iron‐based superconductors. A central question in nematicity is whether it is driven by Fermi surface instability in momentum space or orbital order (polarization) in real space, especially as nematicity intertwines with superconductivity. FeSe/SrTiO 3 (STO), where nematicity occurs without long‐range magnetic order, is an ideal platform for studying the nature and origin of the electronic nematicity. Here, direct evidence of d ‐wave nematic order in two monolayer FeSe/STO using angle‐resolved photoemission spectroscopy is presented, revealing a remarkable degeneracy of d xz and d yz bands at the Brillouin zone center, but a significant band separation at the zone corner. This momentum‐dependent nematicity demonstrates that nematicity in FeSe/STO originates from the d ‐wave Fermi surface instability of the Pomeranchuk‐type, offering insights into the relationship between nematicity and superconductivity. The results establish 2D FeSe thin film as a powerful platform for investigating quantum physics under complex intertwinement.

Source: Advanced Science

DOI: 10.1002/advs.202516394