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 (\[\pm1\]) 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.

Details

Title
Topological kink plasmons on magnetic-domain boundaries
Author
Jin, Dafei 1 ; Yang, Xia 2   VIAFID ORCID Logo  ; Christensen, Thomas 3 ; Freeman, Matthew 4 ; Wang, Siqi 2 ; King, Yan Fong 2 ; Gardner, Geoffrey C 5 ; Fallahi, Saeed 6 ; Hu, Qing 7 ; Wang, Yuan 2 ; Engel, Lloyd 4 ; Zhi-Li, Xiao 8 ; Manfra, Michael J 9   VIAFID ORCID Logo  ; Fang, Nicholas X 7 ; Zhang, Xiang 10   VIAFID ORCID Logo 

 Nanoscale Science and Engineering Center, University of California, Berkeley, CA, USA; Center for Nanoscale Materials, Argonne National Laboratory, Argonne, IL, USA 
 Nanoscale Science and Engineering Center, University of California, Berkeley, CA, USA 
 Department of Physics, Massachusetts Institute of Technology, Cambridge, MA, USA 
 National High Magnetic Field Laboratory, Tallahassee, FL, USA 
 Microsoft Quantum Purdue and Birck Nanotechnology Center, Purdue University, West Lafayette, IN, USA 
 Department of Physics and Astronomy and Birck Nanotechnology Center, Purdue University, West Lafayette, IN, USA 
 Department of Mechanical Engineering, Massachusetts Institute of Technology, Cambridge, MA, USA 
 Material Science Division, Argonne National Laboratory, Argonne, IL, USA 
 Microsoft Quantum Purdue, Department of Physics and Astronomy, Birck Nanotechnology Center, Schools of Electrical and Computer Engineering and Materials Engineering, Purdue University, West Lafayette, IN, USA 
10  Nanoscale Science and Engineering Center, University of California, Berkeley, CA, USA; Faculties of Sciences and Engineering University of Hong Kong, Hong Kong SAR, PR, China 
Pages
1-9
Publication year
2019
Publication date
Oct 2019
Publisher
Nature Publishing Group
e-ISSN
20411723
Source type
Scholarly Journal
Language of publication
English
ProQuest document ID
2302410363
Copyright
© 2019. This work is published under http://creativecommons.org/licenses/by/4.0/ (the “License”). Notwithstanding the ProQuest Terms and Conditions, you may use this content in accordance with the terms of the License.