Mountain pass for the Ginzburg-Landau energy in a strip: solitons and solitonic vortices
Amandine Aftalion, Luc Nguyen
TL;DR
This work analyzes the Ginzburg–Landau energy in an infinite strip under phase imprinting, revealing a width-dependent transition between soliton and solitonic vortex behaviors in 2D and extending the framework to 3D cylinders. It develops a variational approach, employing minimization under symmetry and mountain-pass techniques to classify critical points and their energies, with precise thresholds involving d = sqrt{2}π/2 and d = sqrt{2} j'_{1,1}. The results explain how solitons can be stable or unstable depending on geometry and how solitonic vortices and multi-vortex configurations arise, connecting to experimental observations of snake instability and vortex formation. The paper also discusses extensions, including radial and higher-dimensional cross-sections and a candidate vortex-ring construction, along with open questions about compactness and ring-like states.
Abstract
Motivated by recent experiments, we study critical points of the Ginzburg-Landau energy in an infinite strip where phase imprinting is applied to half of the domain. We prove that there is a critical width of the cross section below which the soliton solution is a mountain pass solution and the minimizer within the subspace of odd functions. Above the critical width, we find that the mountain pass solution is a vortex with a solitonic behaviour in the infinite direction, called a solitonic vortex. Moreover, depending on the width, we prove that the minimizer in a space with some symmetries can display one or several solitonic vortices. While the problem shares some similarities with the analysis of stability and minimality of the Ginzburg-Landau vortex of degree one in a disk or the whole plane, the change in geometry introduces subtle analytical differences. Extensions to the case of an infinite cylinder in 3D are also given.
