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Topological kink plasmons on magnetic-domain boundaries
Dafei Jin1,2, Yang Xia1, Thomas Christensen3
1Nanoscale Science and Engineering Center, University of California, Berkeley, CA, 94706, USA.
Nature Communications
|October 10, 2019
Summary
Researchers observed unique kink magnetoplasmons (KMPs) in a GaAs/AlGaAs system. These topologically protected edge modes propagate unidirectionally along magnetic domain boundaries, offering tunable, nonreciprocal signal transmission.
Area of Science:
- Condensed Matter Physics
- Materials Science
- Quantum Phenomena
Background:
- Topological materials with time-reversal-breaking magnetic fields exhibit protected one-way edge modes.
- These edge modes typically occur at physical material edges.
- Theory predicts unique 'kink modes' at magnetic domain boundaries within homogeneous materials, but experimental evidence is scarce.
Purpose of the Study:
- To experimentally demonstrate and characterize topologically-protected kink modes.
- To investigate the properties and potential applications of these novel edge modes in a realistic system.
Main Methods:
- Utilized a GaAs/AlGaAs two-dimensional electron gas (2DEG) system.
- Externally patterned a magnetic field to create domain boundaries within the uniform 2DEG.
- Investigated high-frequency electromagnetic responses to detect and analyze kink magnetoplasmons (KMPs).
Main Results:
- Observed topologically-protected high-frequency kink magnetoplasmons (KMPs) at the projected magnetic domain boundary.
- KMPs propagate unidirectionally along the boundary, protected by differing gap Chern numbers across domains.
- Demonstrated significant tunability of KMPs via applied magnetic fields and gate voltages, with clear nonreciprocity signatures.
Conclusions:
- Successfully demonstrated the existence of kink magnetoplasmons in a 2DEG system, validating theoretical predictions.
- KMPs offer a novel platform for topologically protected, unidirectional signal propagation in homogeneous magnetic materials.
- The observed tunability and nonreciprocity suggest potential for advanced spintronic and photonic devices.
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