arXiv subjects
Publications and source records attributed to Philippe Kerdelhué.
The aim of this article is to prove that for the graphene model like for a model considered by the physicist Hou on a kagome lattice, there exists a formula which is similar to the one obtained by Chambers for the Harper model. As an application, we propose a semi-classical analysis of the spectrum of the Hou butterfly near a flat band.
We study in a semiclassical regime a two-dimensional magnetic periodic Schrödinger operator. We first review some results for the square (Harper), triangular and hexagonal (case of the graphene) lattices. Then we study the case considered by Hou when the periodicity is given by a kagome lattice. We reduce the problem to the study of discrete and pseudodifferential operators and obtain pictures similar to Hofstadter's butterfly. We prove the existence of flat bands, which do not occur in the three previous cases.
We consider the evolution operator exp(-it(-Delta+V)) associated with a Schrödinger operator on a Riemannian manifold (M,g). We are interested in the dependence of this operator on V running in L^p(M). Under a geometrical hypothetis, we show the unstability for p