Topological defect induced phase separation in a holographic system

Abstract

We investigate the coupled dynamics of symmetry breaking and phase separation during quenches across the critical point in a first-order phase transition. Based on the Einstein-Maxwell-scalar theory, we construct a holographic superfluid model with $\mathbb{Z}_2$ symmetry. By introducing higher-order nonlinear terms $λΨ^4$ and $τΨ^6$ into the scalar field potential, we realize a rich phase structure, which enables us to study the coupling effects between symmetry breaking and phase separation. Furthermore, by preparing initial conditions with well-defined spatial partitions, we discover a new triggering mechanism for the invasion phenomenon, namely that kinks serve as triggering sites for the phase separation process. This study reveals a novel coupling mechanism between topological defects and phase separation, enriches our understanding of nonequilibrium structure formation in strongly coupled systems.

Figures (9)

• Figure 1: The condensate and free energy for $\lambda=0$ and $\tau=0$. The dashed lines correspond to the normal solution, and the solid lines correspond to the superfluid solution.
• Figure 2: The condensate and free energy for $\lambda=-4$ and $\tau=2.7$. The black dashed lines correspond to the normal solution, and the black solid lines correspond to the superfluid solution. The red solid lines correspond to the grand canonical ensemble (fix chemical potential $\mu$) superfluid solution. The blue dashed line denotes the inflection point in the grand canonical ensemble. Where $G_n$ denotes the free energy of the normal solution.
• Figure 3: Phase diagram of the holographic system, where $NSSP$ denotes no stable superfluid phase.
• Figure 4: The process of topological defect formation during a quench from $\rho_i = 1.3$ to $\rho_f = 1.52$ in a second-order phase transition (Ref. \ref{['co2nd']}) with $L_x=400$, $n_x=1200$, and $\tau_Q=0.1$. The left panel shows the time evolution of the condensate. The middle panel presents a density plot of the condensate as a function of both time and space, where the color bar indicates the magnitude of the condensate. The right panel displays the spatial distribution of the condensate at $t = 200$.
• Figure 5: The process of phase separation during a quench from $\rho_i = 1.68$ to $\rho_f = 1.52$ in a first-order phase transition (Ref. \ref{['co1st']}) with $L_x=400$, $n_x=1200$, and $\tau_Q=0.1$. The left panel shows the time evolution of the condensate. The middle panel presents a density plot of the condensate as a function of both time and space, where the color bar indicates the magnitude of the condensate. The right panel displays the spatial distribution of the condensate at $t = 1000$.