In eq. 1 of this reference, the authors present the following Hamiltonian for the 2-band gapped chiral fermion model that can describe many systems including various semiconductors, N-layer graphene, etc: $$ {H}({k}) = \begin{pmatrix} \Delta & \alpha(|{k}|)e^{i w \phi_k}\\ \alpha(|{k}|)e^{-i w \phi_k} & -\Delta \end{pmatrix}, $$ where the energy gap is $2\Delta$, $\phi_{{k}}=\tan^{-1}({k_y}/{k_x})$ and $\alpha(|{k}|)=\alpha|{k}|^\gamma$.
Does anyone know where this Hamiltonian was first used in the literature (specifically in condensed matter)? All the several works I have seen use it (or some version of it) take its form for granted. For instance, I looked at citations [5-10], [12-17] of the referenced work. Additionally I looked at some Google Scholar results (including this thesis). But could not find it. Perhaps because it probably was not named 'gapped chiral fermion' in its original form?
