Axionic charge-density wave in the Weyl semimetal (TaSe4)2I.
J Gooth1, B Bradlyn2, S Honnali3
1Max Planck Institute for Chemical Physics of Solids, Dresden, Germany. johannes.gooth@cpfs.mpg.de.
Nature
|October 8, 2019
Summary
Researchers observed axionic charge-density waves in Weyl semimetals, detecting anomalous magnetoelectric transport. This finding provides experimental evidence for axions in topological condensed matter systems.
Area of Science:
- Condensed Matter Physics
- Topological Materials
- Quantum Phenomena
Background:
- Axion insulators are correlated topological phases predicted from charge-density waves in Weyl semimetals.
- The sliding mode (phason) in these phases acts as an axion, potentially causing anomalous magnetoelectric effects.
- Experimental detection of axionic charge-density waves has remained elusive.
Purpose of the Study:
- To experimentally detect the predicted axionic charge-density wave.
- To investigate anomalous magnetoelectric transport phenomena in Weyl semimetals.
- To provide evidence for axions in condensed matter systems.
Main Methods:
- Investigated the charge-density wave Weyl semimetal (TaSe4)2I.
- Measured magnetoconductance under collinear electric and magnetic fields.
- Analyzed the angular dependence of magnetoconductance by rotating the magnetic field.
Main Results:
- Observed a large positive magnetoconductance contribution in the charge-density wave sliding mode.
- This positive contribution is linked to the axionic contribution of the chiral anomaly to the phason current.
- The effect is locked to collinear electric and magnetic fields, with angular dependence consistent with axionic charge-density wave transport.
Conclusions:
- The study provides the first experimental evidence for axionic charge-density waves.
- Demonstrates that axions can be detected in strongly correlated topological condensed matter systems.
- Highlights the role of the chiral anomaly in the observed anomalous transport effects.
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