Topological kink plasmons on magnetic-domain boundaries
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 ($$\pm1$$ ± 1 ) 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.
Document Details
- Document Type
- Pub Defense Publication
- Publication Date
- Oct 08, 2019
- Source ID
- 10.1038/s41467-019-12092-x
Entities
People
- Dafei Jin
- Geoffrey C. Gardner
- King Yan Fong
- Lloyd Engel
- Matthew Freeman
- Michael J Manfra
- Nicholas X. Fang
- Qing Hu
- Saeed Fallahi
- Siqi Wang
- Thomas Christensen
- Xiang Zhang
- Yang Xia
- Yuan Wang
- Zhi-li Xiao
Organizations
- Air Force Office of Scientific Research