In the first part of this
paper, we give a lower bound for the spectrum of the Laplacian on minimal
hypersurfaces immersed into ℍm× ℝ. As an application, in dimension 2, we prove
that a complete minimal surface with finite total extrinsic curvature has finite index.
In the second part, we consider the operator L = Δg+ a + bKg on a complete
noncompact surface (M2,g). Assuming that L is nonnegative for some constants
a > 0 and b > 1∕4, we show that the infimum of the spectrum of M2 is bounded from
above by a∕(4b − 1). We apply this result to stable minimal surfaces immersed into
homogeneous 3-manifolds.
Keywords
minimal hypersurface, eigenvalue estimate, stability, index