Coherent Phonon Pairs and Rotational Symmetry Breaking of Charge Density Wave Order in the Kagome Superconductor CsV$_3$Sb$_5$
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arXiv
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| Autori principali: | , , , , , , |
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| Natura: | Preprint |
| Pubblicazione: |
2025
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| _version_ | 1866908539131265024 |
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| author | Deng, Qinwen Tan, Hengxin Ortiz, Brenden R. Salinas, Andrea Capa Wilson, Stephen D. Yan, Binghai Wu, Liang |
| author_facet | Deng, Qinwen Tan, Hengxin Ortiz, Brenden R. Salinas, Andrea Capa Wilson, Stephen D. Yan, Binghai Wu, Liang |
| contents | In this work, we perform ultrafast time-resolved reflectivity measurements to study the symmetry breaking in the charge-density wave (CDW) phase of CsV$_3$Sb$_5$. By extracting the coherent phonon spectrum in the CDW phase of CsV$_3$Sb$_5$, we discover close phonon pairs near 1.3 THz and 3.1 THz, as well as a new mode at 1.84 THz. The 1.3 THz phonon pair and the 1.84 THz mode are observed up to the CDW transition temperature. Combining density-functional theory calculations, we point out these phonon pairs arise from the coexistence of Star-of-David and inverse Star-of-David distortions combined with six-fold rotational symmetry breaking. An anisotropy in the magnitude of transient reflectivity change is also revealed at the onset of CDW order. Our results thus indicate broken six-fold rotational symmetry in the charge-density wave state of CsV$_3$Sb$_5$, along with the absence of nematic fluctuation above T$_{\text{CDW}}$. Meanwhile, the measured coherent phonon spectrum in the CDW phase of CsV$_3$Sb$_{5-\text{x}}$Sn$_\text{x}$ with x = 0.03-0.04 matches with staggered inverse Star-of-David with interlayer $π$ phase shift. This CDW structure contrasts with undoped CsV$_3$Sb$_5$ and explains the evolution from phonon pair to a single mode at 1.3 THz by x = 0.03-0.04 Sn-doping. |
| format | Preprint |
| id |
arxiv_https___arxiv_org_abs_2503_07442 |
| institution | arXiv |
| publishDate | 2025 |
| record_format | arxiv |
| spellingShingle | Coherent Phonon Pairs and Rotational Symmetry Breaking of Charge Density Wave Order in the Kagome Superconductor CsV$_3$Sb$_5$ Deng, Qinwen Tan, Hengxin Ortiz, Brenden R. Salinas, Andrea Capa Wilson, Stephen D. Yan, Binghai Wu, Liang Materials Science In this work, we perform ultrafast time-resolved reflectivity measurements to study the symmetry breaking in the charge-density wave (CDW) phase of CsV$_3$Sb$_5$. By extracting the coherent phonon spectrum in the CDW phase of CsV$_3$Sb$_5$, we discover close phonon pairs near 1.3 THz and 3.1 THz, as well as a new mode at 1.84 THz. The 1.3 THz phonon pair and the 1.84 THz mode are observed up to the CDW transition temperature. Combining density-functional theory calculations, we point out these phonon pairs arise from the coexistence of Star-of-David and inverse Star-of-David distortions combined with six-fold rotational symmetry breaking. An anisotropy in the magnitude of transient reflectivity change is also revealed at the onset of CDW order. Our results thus indicate broken six-fold rotational symmetry in the charge-density wave state of CsV$_3$Sb$_5$, along with the absence of nematic fluctuation above T$_{\text{CDW}}$. Meanwhile, the measured coherent phonon spectrum in the CDW phase of CsV$_3$Sb$_{5-\text{x}}$Sn$_\text{x}$ with x = 0.03-0.04 matches with staggered inverse Star-of-David with interlayer $π$ phase shift. This CDW structure contrasts with undoped CsV$_3$Sb$_5$ and explains the evolution from phonon pair to a single mode at 1.3 THz by x = 0.03-0.04 Sn-doping. |
| title | Coherent Phonon Pairs and Rotational Symmetry Breaking of Charge Density Wave Order in the Kagome Superconductor CsV$_3$Sb$_5$ |
| topic | Materials Science |
| url | https://arxiv.org/abs/2503.07442 |