Normalized solutions and stability for biharmonic Schrödinger equation with potential on waveguide manifold

In this paper, we study the following biharmonic Schrödinger equation with potential and mixed nonlinearities \begin{equation*} \left{\begin{array}{ll}Δ^2 u +V(x,y)u+λu =μ|u|^{p-2}u+|u|^{q-2}u,\ (x, y) \in Ω_r \times $\mathbb{T}$^n, \ \int_{Ω_r\times$\mathbb{T}$^n}u^2dxdy=Θ,\end{array} \right. \end{equation*} where ${\mathrm{\Omega }}_r\subset {\mathbb{R}}^d$ is an open bounded convex domain, $r>0$ is large and $\mu \in \mathbb{R}$. The exponents satisfy $2<p<2+\frac{8}{d+n}<q<4^{\ast }=\frac{2(d+n)}{d+n-4}$, so that the nonlinearity is a combination of a mass subcritical and a mass supercritical term. Under some assumptions on $V(x,y)$ and $\mu$, we obtain the several existence results on waveguide manifold. Moreover, we also consider the orbital stability of the solution.