[Taehyeok Kim and Prof. Hongki Min] Unveiling three types of fermions in a nodal ring topological semimetal through magneto-optical transitions (Published in Physical Review Letters)
SrAs₃ hosts a single nodal ring in the Brillouin zone without interference from trivial bands around the Fermi level. Using high-field magneto-reflectivity, we tracked Landau-level transitions and revealed three types of low-energy quasiparticles in the single nodal ring. Based on the model calculations, we analyzed the scaling behavior of the Landau levels for the magnetic field to identify Dirac, semi-Dirac, and classical fermions coexisting in a single material. Semi-Dirac fermions—rarely accessible in ordinary nodal-line systems—emerge here when the curved nodal ring tangentially contacts a momentum plane, producing linear–quadratic dispersion. Because band tilt and spin–orbit coupling in SrAs3 distort the ideal scaling behavior, our model calculations were essential to match each spectral peak to its fermionic origin.
This work is done in collaboration with Mr. Jiwon Jeon and Prof. Eunjip Choi at University of Seoul, along with other collaborators.
Authors: Jiwon Jeon* (UOS), Taehyeok Kim* (SNU), Jiho Jang (SNU), Hoil Kim (POSTECH), Mykhaylo Ozerov (NHMFL), Jun Sung Kim (POSTECH), Hongki Min** (SNU), and Eunjip Choi** (UOS)
(*co-first authors, **co-corresponding authors)
Title: Unveiling three types of fermions in a nodal ring topological semimetal through magneto-optical transitions
Journal: Phys. Rev. Lett. 135, 086901 (2025)
Publication date: 19 August 2025