Magnetic-fluctuation-driven suppression of spin-orbit hybridization in the surface ferromagnet GdAg$_2$/Ag(111)

TL;DR

This study reveals that magnetic fluctuations can suppress spin-orbit hybridization in the GdAg$_2$/Ag(111) surface ferromagnet, affecting topological band features and Berry curvature, with implications for non-Hermitian physics.

Contribution

It demonstrates how magnetic fluctuations influence spin-orbit hybridization and Berry curvature in a 2D ferromagnetic system, introducing a non-Hermitian perspective.

Findings

Spin fluctuations preserve nodal-line crossings above Curie temperature.

SOC-induced hybridization develops only at low temperatures.

Suppression of hybridization is due to spin decoherence and scattering.

Abstract

Magnetic materials hosting topological band structures have attracted intense interest due to the interplay between magnetism and spin-orbit coupling (SOC). Here, using temperature- and polarization-dependent angle-resolved photoemission spectroscopy, we investigate the surface ferromagnet GdAg$_2$/Ag(111), a two-dimensional system with Weyl-nodal-line-like band crossings. We find that spin fluctuations preserve the nodal-line-derived band crossings even above the Curie temperature, while SOC-induced hybridization develops only at low temperatures, as evidenced by spectral-weight redistribution. The suppression of the hybridization at high temperature is attributed to spin decoherence and band-dependent scattering, captured by an effective non-Hermitian framework. Our results establish magnetic fluctuations as a control knob for SOC-induced hybridization and associated Berry curvature, and highlight magnetic systems as a platform for exploring non-Hermitian band physics.