Skip to main content
eScholarship
Open Access Publications from the University of California

Topological kink plasmons on magnetic-domain boundaries.

  • Author(s): Jin, Dafei
  • Xia, Yang
  • Christensen, Thomas
  • Freeman, Matthew
  • Wang, Siqi
  • Fong, King Yan
  • Gardner, Geoffrey C
  • Fallahi, Saeed
  • Hu, Qing
  • Wang, Yuan
  • Engel, Lloyd
  • Xiao, Zhi-Li
  • Manfra, Michael J
  • Fang, Nicholas X
  • Zhang, Xiang
  • et al.
Abstract

Two-dimensional topological materials bearing time reversal-breaking magnetic fields support protected one-way edge modes. Normally, these edge modes adhere to physical edges where material properties change abruptly. However, even in homogeneous materials, topology still permits a unique form of edge modes - kink modes - residing at the domain boundaries of magnetic fields within the materials. This scenario, despite being predicted in theory, has rarely been demonstrated experimentally. Here, we report our observation of topologically-protected high-frequency kink modes - kink magnetoplasmons (KMPs) - in a GaAs/AlGaAs two-dimensional electron gas (2DEG) system. These KMPs arise at a domain boundary projected from an externally-patterned magnetic field onto a uniform 2DEG. They propagate unidirectionally along the boundary, protected by a difference of gap Chern numbers ([Formula: see text]) in the two domains. They exhibit large tunability under an applied magnetic field or gate voltage, and clear signatures of nonreciprocity even under weak-coupling to evanescent photons.

Main Content
Current View