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arXiv · 2111.02323

Observation of Dirac Charge Density Waves in Bi$_2$Te$_2$Se

Adrian Ruckhofer·Giorgio Benedek·Martin Bremholm·Wolfgang E. Ernst·Anton Tamtögl
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Abstract

While parallel segments in the Fermi level contours, often found at the surfaces of topological insulators (TIs) would imply "strong" nesting conditions, the existence of charge density waves (CDWs) - periodic modulations of the electron density - has not been verified up to now. Here, we report the observation of a CDW at the surface of the Bi$_2$Te$_2$Se(111), below $\approx 350\,$K by helium atom scattering, and thus experimental evidence of a CDW involving Dirac topological electrons. Deviations of the order parameter observed below $180\,$K and a low temperature break of time reversal symmetry suggest the onset of a spin density wave with the same period as the CDW in presence of a prominent electron-phonon interaction originating from the Rashba spin-orbit coupling.

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Adrian Ruckhofer, Giorgio Benedek, Martin Bremholm, Wolfgang E. Ernst, Anton Tamtögl. 2021-11-03. Observation of Dirac Charge Density Waves in Bi$_2$Te$_2$Se. https://doi.org/10.3390/nano13030476

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