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Light-induced vortex matter from transient domain walls in ultrafast experiments

by Dr Lingxian Kong (孔令贤) (KTH Royal Institute of Technology)

→ Asia/Shanghai
Tsung-Dao Lee Institute/N4F-N400 - meeting room (Tsung-Dao Lee Institute)

Tsung-Dao Lee Institute/N4F-N400 - meeting room

Tsung-Dao Lee Institute

70
Description

Host: Prof. Vadim Grinenko  

Venue: TDLI Meeting Room N400

Tencent Meeting link:  https://meeting.tencent.com/dm/vrsm5QXAp6DZ

Meeting ID: 229842433, no password

 

 

Abstract:

In ultrafast experiments, an optical pump pulse often generates transient domain walls of the order parameter in materials with spontaneous symmetry breaking, due to either a finite penetration depth of light on a three-dimensional (3D) material, or a finite spot size on a two-dimensional (2D) material. We show that the domain wall decays due to unstable order parameter fluctuations. We study a generic system with U(1)-symmetric order, and those with an additional weak Z2 (U(1)-symmetry-breaking) term, representing the charge-density-wave (CDW) orders in recent experiments. During the first stage of the decay dynamics, exponentially growing thermal fluctuations convert the domain wall into an interface with randomly distributed topological defects. In the second stage, the topological defects undergo a coarsening dynamics within the interface. For a 2D interface in a 3D system, the coarsening dynamics leads to a diffusive growth of the correlation length. For a one-dimensional (1D) interface in a 2D system with the weak Z2 term, the correlation-length growth shows a crossover from diffusive to sub-diffusive behavior.

 

Biography:

Lingxian Kong is currently a postdoctoral researcher in the Division of Condensed Matter Theory at KTH Royal Institute of Technology. He received his Ph.D. from Peking University in 2025 and his bachelor’s degree from Shanghai Jiao Tong University in 2020. His research focuses on the collective dynamics of many-body systems, including the equilibrium and nonequilibrium dynamics of exciton condensates, multicomponent superconductors, and related systems.