Abstract

We carry out the spectral analysis of matrix valued perturbations of three-dimensional Dirac operators with variable magnetic field of constant direction. Under suitable assumptions on the magnetic field and on the pertubations, we obtain a limiting absorption principle, we prove the absence of singular continuous spectrum in certain intervals and state properties of the point spectrum. Various situations, for example, when the magnetic field is constant, periodic or diverging at infinity, are covered. The importance of an internal-type operator (a two-dimensional Dirac operator) is also revealed in our study. The proofs rely on commutator methods. (C) 2004 American Institute of Physics.