Minimizing solutions of degenerate Allen-Cahn equations with three wells in $\mathbb{R}^2$

Abstract

We characterize all minimizers of the vector-valued Allen-Cahn equation in $\mathbb{R}^2$ under the assumption that the potential $W$ has three wells and that the associated degenerate metric does not satisfy the usual strict triangle inequality. These minimizers depend on one variable only in a suitable coordinate system. In particular, we show that no minimizing solutions to $ \Delta u=\nabla W(u)$ on $\mathbb{R}^2$ can approach the three distinct values of the potential wells.