  We are concerned with the multiplicity of positive solutions for the singular
superlinear and subcritical Schr\"odinger equation
  $$
  \begin{array}{c}
  -\Delta u +V(x)u=\lambda a(x)u^{-\gamma}+b(x)u^{p}~\mbox{in}~ \mathbb{R}^{N},
  \end{array}
  $$
  beyond the Nehari extremal value, as defined in Il'yasov [Topol. Methods
Nonlinear Anal., 2017], when the potential $b \in L^{\infty}(\mathbb{R}^{N})$
may change its sign, $0<a\in L^{\frac{2}{1+\gamma}}(\mathbb{R}^{N})$, $V$ is a
positive continuous function, $N\geq 3$ and $\lambda>0$ is a real parameter.
The main difficulties come from the non-differentiability of the energy
functional and the fact that the intersection of the boundaries of the
connected components of the Nehari set is non empty. We overcome these
difficulties by exploring topological structures of that boundary to build
non-empty sets whose boundaries have empty intersection and minimizing over
them by controlling the energy level.
