Castro-Montes Alicia G, Marín Juan F, Teca-Wellmann Diego, González Jorge A, García-Ñustes Mónica A
Instituto de Física, Pontificia Universidad Católica de Valparaíso, Casilla 4059, Chile.
Departamento de Física, Universidad Técnica Federico Santa María, Casilla 110-V, Valparaíso, Chile.
Chaos. 2020 Jun;30(6):063132. doi: 10.1063/5.0006226.
We investigate analytically and numerically the stability of bubble-like fluxons in disk-shaped heterogeneous Josephson junctions. Using ring solitons as a model of bubble fluxons in the two-dimensional sine-Gordon equation, we show that the insertion of coaxial dipole currents prevents their collapse. We characterize the onset of instability by introducing a single parameter that couples the radius of the bubble fluxon with the properties of the injected current. For different combinations of parameters, we report the formation of stable oscillating bubbles, the emergence of internal modes, and bubble breakup due to internal mode instability. We show that the critical germ depends on the ratio between its radius and the steepness of the wall separating the different phases in the system. If the steepness of the wall is increased (decreased), the critical radius decreases (increases). Our theoretical findings are in good agreement with numerical simulations.
我们通过解析和数值方法研究了盘状非均匀约瑟夫森结中泡状磁通子的稳定性。使用环形孤子作为二维正弦 - 戈登方程中泡状磁通子的模型，我们表明同轴偶极电流的插入可防止它们坍塌。我们通过引入一个将泡状磁通子的半径与注入电流的特性耦合的单一参数来表征不稳定性的起始。对于不同的参数组合，我们报告了稳定振荡泡的形成、内部模式的出现以及由于内部模式不稳定性导致的泡破裂。我们表明临界胚芽取决于其半径与系统中分隔不同相的壁的陡峭程度之间的比率。如果壁的陡峭程度增加（减小），临界半径减小（增加）。我们的理论发现与数值模拟结果吻合良好。
