Counterexample to strong diamagnetism for the magnetic Robin Laplacian

Abstract

We determine a counterexample to strong diamagnetism for the Laplace operator in the unit disc with a uniform magnetic field and Robin boundary condition. The example follows from the accurate asymptotics of the lowest eigenvalue when the Robin parameter tends to $-\infty$.

Added Reference [11]; modified the formulae in (1.6), (1.10) and (1.13)