Fig. 2: Illustration of the decay of the domain wall.
From: Fate of transient order parameter domain walls in ultrafast experiments
a The ‘Mexican hat’ free energy landscape (the potential part) of Eq. (2) plotted on the complex plane of ψ. b, c The phase of ψ plotted on the y– z plane at (b) t = t0 and (c) t ≥ tc, showing the domain wall at z = 0. The ψ and free energy along the gray, black, and white lines are also plotted in (a). In the initial domain-wall configuration, ψ = ψ0(z) changes from \(-\sqrt{| \alpha | }\) to \(\sqrt{| \alpha | }\) crossing the potential peak along the gray line. To lower the energy, ψ fluctuates in the imaginary direction. After tc, random phase domains appear on the interface. The loop denoted by black and white lines in (c) encloses a vortex with a phase winding 2π. In a 2D interface of a 3D system, the interface becomes full of vortex-strings as shown in Fig. 1.
