Raman spectroscopic signature of fractionalized excitations in the harmonic-honeycomb iridates β- and γ-Li2IrO3.

Fractional excitations in quantum spin systems lead to exotic particles predicted in theory but difficult to observe in experiments. Here, Glamazda et al. report the dynamical Raman response of β- and γ-Li2IrO3 is dominated by thermal damping of fermionic excitations, suggesting the emergence of Majorana fermions from spin fractionalization.