Current Induced Fingering Instability in Magnetic Domain Walls

Fingering Instability of Dislocations and Related Defects

We identify a fundamental morphological instability of mobile dislocations in crystals and related line defects. A positive gradient in the local driving force along the direction of defect motion destabilizes long-wavelength vibrational modes, producing a ``fingering'' pattern. The minimum unstable wavelength scales as the inverse square root of the force gradient. We demonstrate the instability's onset in simulations of a screw dislocation in Al (via molecular dynamics) and of a vortex in a 3-d XY ``rotator'' model.

Fluid driven fingering instability of a confined elastic meniscus

When a fluid is pumped into a cavity in a confined elastic layer, at a critical pressure, destabilizing fingers of fluid invade the elastic solid along its meniscus (Saintyves, Dauchot, and Bouchaud, 2013). These fingers occur without fracture or loss of adhesion and are reversible, disappearing when the pressure is decreased. We develop an asymptotic theory of pressurized highly elastic layers trapped between rigid bodies to explain these observations, with predictions for the critical fluid pressure for fingering, and the finger wavelength. We also show that the theory links this fluid-drive…

超越线性稳定性：异质性诱导的裂纹前缘指状扩展

Beyond linear stability: Heterogeneity-induced fingering of crack fronts

本文研究弹性界面超越线性区域的稳定性，通过断裂力学模拟发现韧性异质性可诱导裂纹前缘失稳形成指状结构，揭示了与经典鞍结分岔不同的全局失稳机制，为理解异质固体的脆性-准脆性转变提供了新视角。

Nucleation and Growth of bundles of Single-Wall Carbon Nanotubes (C-SWNTs): the Benard-Marangoni Instability (BMI) model

A complete explanation of the synthesis of metal-catalyst nanoparticles, and the subsequent nucleation and growth of bundles of C-SWNTs is introduced using a novel model. It is shown that the synthesis process leads to the formation of a liquid layer supersaturated in carbon surrounding each metallic-catalyst nanoparticle. The onset of a solutal Bénard-Marangoni instability and the subsequent formation of patterns of hexagonal convection cells in the liquid layer is predicted and quantified by linear and weakly nonlinear analyses. The nucleation and growth of a C-SWNT at the center of convecti…

高交换铁磁纳米线中成核不稳定性先于相对论性畴壁输运

Nucleation instability preempts relativistic domain wall transport in high-exchange ferrimagnetic nanowires

本研究通过磁光克尔效应显微镜观察GdCo纳米线中的自旋轨道矩驱动畴壁运动，发现成核不稳定性阻止了相对论性输运，并绘制了畴壁输运与成核不稳定性的动态相界。

Intrinsic structural instabilities of domain walls driven by gradient couplings: meandering anferrodistortive-ferroelectric domain walls in BiFeO3

Using Landau-Ginzburg-Devonshire approach, we predict the intrinsic instability of the ferroelectric-ferroelastic domain walls in the multiferroic BiFeO3 emerging from the interplay between the gradient terms of the antiferrodistortive and ferroelectric order parameters at the walls. These instabilities are the interface analogue of the structural instabilities in the vicinity of phase coexistence in the bulk; and so they do not steam from incomplete polarization screening in thin films or its spatial confinement, electrostrictive or flexoelectric coupling. The effect of BiFeO3 material parame…