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arXiv · 2108.11690

Emergent nematicity and intrinsic vs. extrinsic electronic scattering processes in the kagome metal CsV$_3$Sb$_5$

Dirk Wulferding·Seungyeol Lee·Youngsu Choi·Qiangwei Yin·Zhijun Tu·Chunsheng Gong·Hechang Lei·Saqlain Yousuf·Jaegu Song·Hanoh Lee·Tuson Park·Kwang-Yong Choi
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Abstract

Fermi surface fluctuations and lattice instabilities in the 2D metallic kagome superconductor CsV$_3$Sb$_5$ are elucidated via polarization-resolved Raman spectroscopy. The presence of a weak electronic continuum in high-quality samples marks the cross-over into the charge-density-wave (CDW) ordered phase, while impurity-rich samples promote strong defect-induced electronic scattering processes that affect the coherence of the CDW phase. CDW-induced phonon anomalies appear below $T_{\mathrm{CDW}}$, with emergent $C2$ symmetry for one of the CDW amplitude modes, alluding to nematicity. In conjunction with symmetry-breaking lattice distortions, a kink-like hardening of the A$_{1g}$ phonon energy at $T_{\mathrm{CDW}}$ signifies a concerted interplay of electronic correlations and electron-phonon coupling in the exotic CDW order.

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Dirk Wulferding, Seungyeol Lee, Youngsu Choi, Qiangwei Yin, Zhijun Tu, Chunsheng Gong, Hechang Lei, Saqlain Yousuf, Jaegu Song, Hanoh Lee, Tuson Park, Kwang-Yong Choi. 2021-08-26. Emergent nematicity and intrinsic vs. extrinsic electronic scattering processes in the kagome metal CsV$_3$Sb$_5$. https://doi.org/10.1103/physrevresearch.4.023215

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