Fig. 2: Phase map, the emergence, and annihilations of the exceptional loops at τ = 2.
From: Photonic topological fermi nodal disk in non-Hermitian magnetic plasma
a The number of nodal disks is due to change by the strength of magnetic field ωc and the electron thermal parameter κ. Along the path crossing the border line, for example the path shown as the yellow arrow in a, the annihilation or emergence of nodal disks could be observed. Three-dimensional (3-D) band structures before and at the critical transition point are given in b and c. Difference of the real part of the eigen frequencies around the nodal disks before, at and after the annihilation of the nodal disks are given in d–f. The dashed lines represent the locations where the difference goes to zero. The positions of the nodal disks are located at the edge of the dashed lines. d Before the coalesce of the two nodal disks. e At the border between the two phases, the two nodal disks would coalesce and dissipate their topological charges. f After the coalesce, the zeros in the e would shift from zero
