Hausdorff measure bounds for nodal sets of Steklov eigenfunctions

Abstract

We study nodal sets of Steklov eigenfunctions in a bounded domain with $\mathcal{C}^2$ boundary. Our first result is a lower bound for the Hausdorff measure of the nodal set: we show that for $u_{\lambda}$ a Steklov eigenfunction, with eigenvalue $\lambda\neq 0$, $\mathcal{H}^{d-1}(\{u_{\lambda}=0\})\geq c_{\Omega}$, where $c_{\Omega}$ is independent of $\lambda$. We also prove an almost sharp upper bound, namely $\mathcal{H}^{d-1}(\{u_{\lambda}=0\})\leq C_{\Omega}\lambda\log(\lambda+e)$.