a The creation of a bound state from itinerant fermions bound to localized fluxes and b from binding only itinerant Majorana fermions. c–h Evolution of Raman data obtained at T = 2 K (open circles) with increasing fields from 0 to 9.5 T. The shaded regions denote the decomposition of the magnetic excitations into well-defined peaks and a continuum of excitations. The solid line is a sum of all excitations. The M1 (blue) and M2 (purple shading) modes at low fields of 0–4.3 T correspond to spin-wave excitations. The mode (M3) may be a higher-energy branch of magnon excitations. The excitation MB (dark red) above the critical field of 6.7 T is assigned to a Majorana bound state. The shoulder (MB’) is either another Majorana bound state or a van-Hove singularity of the Majorana continuum excitations.