GAP OPENING IN THE SPECTRUM OF SOME DIRAC-LIKE PSEUDO-DIFFERENTIAL OPERATORS

In this paper, we study the opening of a spectral gap for a class of 2-dimensional periodic Hamiltonians which include those modelling multilayer graphene. The kinetic part of the Hamiltonian is given by σ·F (−i∇), where σ denotes the Pauli matrices and F is a sufficiently regular vector-valued function which equals 0 at the origin and grows at infinity. Its spectrum is the whole real line. We prove that a gap appears for perturbations in a certain class of periodic matrix-valued potentials depending on F, and we study how this gap depends on different parameters.