arXiv subjects

Germán Miranda

Publications and source records attributed to Germán Miranda.

4 recordsLinked to original sources

arXiv2026

Friedlander's inequality and the de Rham complex

Inequalities between Dirichlet and Neumann eigenvalues of the Laplacian and of other differential operators have been intensively studied in the past decades. The aim of this paper is to introduce differential forms and the de Rham complex in the study of such inequalities. We show how differential forms lie hidden at the heart of the work of Rohleder on inequalities between Dirichlet and Neumann eigenvalues for the Laplacian on planar domains.

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arXiv2024

The magnetic Laplacian on the Disc for strong magnetic fields

The magnetic Laplacian on a planar domain under a strong constant magnetic field has eigenvalues close to the Landau levels. We study the case when the domain is a disc and the spectrum consists of branches of eigenvalues of one dimensional operators. Under Neumann boundary condition and strong magnetic field, we derive asymptotics of the eigenvalues with accurate estimates of exponentially small remainders. Our approach is purely variational and applies to the Dirichlet boundary condition as well, which allows us to recover recent results by Baur and Weidl.

math.SP↗

arXiv2023

Discrete spectrum of the magnetic Laplacian on almost flat magnetic barriers

The magnetic Laplacian with a step magnetic field has been intensively studied during the last years. We adapt the construction introduced by Bonnaillie-Noël, Fournais, Kachmar and Raymond to prove the existence of bound states of a new effective operator involving a magnetic step field on a domain with an almost flat magnetic barrier. This result emphasizes the fact that even a small non-smoothness of the discontinuity region can cause the appearance of eigenvalues below the essential spectrum. We also give an example where this effective operator arises.

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arXiv2022

Non-monotonicity for the 3D magnetic Robin Laplacian

Previous works provided several counterexamples to monotonicity of the lowest eigenvalue for the magnetic Laplacian in the two-dimensional case. However, the three-dimensional case is less studied. We use the results obtained by Helffer, Kachmar and Raymond to provide one of the first counterexamples in 3D. Considering the Robin magnetic Laplacian on the unit ball with a constant magnetic field, we show the non-monotonicity of the lowest eigenvalue asymptotics when the Robin parameter tends to $+\infty$.

math.SP↗