ORBITAL DIAMAGNETISM OF 2-DIMENSIONAL ELECTRONS

Different direct perturbation theories show that the Peierls substitution leads to quantitative and qualitative errors in calculations of the energy difference with and without magnetic field for both nearly free and tight-binding two-dimensional electrons. The sources of these errors are clarified. The lowering of the electron kinetic energy in a magnetic field is shown to be in general an artifact of the Peierdls substution. Spontaneous orbital ferromagnetism is shown to be impossible. Credibility of the usual theory of Landau diamagnetism for two dimensions is reestablished.