Isoparametric foliation and Yau conjecture on the first eigenvalue, II

This is a continuation of [23], which investigated the first eigenvalues of minimal isoparametric hypersurfaces with g=4g=4 distinct principal curvatures and focal submanifolds in unit spheres. For the focal submanifolds with g=6g=6, the present paper obtains estimates on all the eigenvalues, among others, giving an affirmative answer in one case to the problem posed in [23], which may be regarded as a generalization of Yau's conjecture. In two of the four unsettled cases in [23] for focal submanifolds M1M1 of OT-FKM-type, we prove the first eigenvalues to be their respective dimensions.