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| Main Authors: | , , , , , , , , , , , |
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| Format: | Preprint |
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2024
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| Subjects: | |
| Online Access: | https://arxiv.org/abs/2401.13886 |
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| _version_ | 1866913208899469312 |
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| author | Gao, Qiang Chan, Yang-hao Jiao, Pengfei Chen, Haiyang Yin, Shuaishuai Tangprapha, Kanjanaporn Yang, Yichen Li, Xiaolong Liu, Zhengtai Shen, Dawei Jiang, Shengwei Chen, Peng |
| author_facet | Gao, Qiang Chan, Yang-hao Jiao, Pengfei Chen, Haiyang Yin, Shuaishuai Tangprapha, Kanjanaporn Yang, Yichen Li, Xiaolong Liu, Zhengtai Shen, Dawei Jiang, Shengwei Chen, Peng |
| contents | Charge density wave (CDW) is a collective quantum phenomenon with a charge modulation in solids1-2. Condensation of electron and hole pairs with finite momentum will lead to such an ordered state3-7. However, lattice symmetry breaking manifested as the softening of phonon modes can occur simultaneously, which makes it difficult to disentangle the origin of the transition8-14. Here, we report a condensed phase in low dimensional HfTe2, whereas angle-resolved photoemission spectroscopy (ARPES) measurements show a metal-insulator transition by lowering the temperature in single triatomic layer (TL) HfTe2. A full gap opening, renormalization of the bands, and emergence of replica bands at the M point are observed in the low temperatures, indicating formation of a CDW in the ground state.Raman spectroscopy shows no sign of lattice distortion within the detection limit. The results are corroborated by first-principles calculations, demonstrating the electronic origin of the CDW. By adding more layers, the phase transition is suppressed and completely destroyed at 3 TL because of the increased screening around the Fermi surface. Interestingly, a small amount of electron doping in 1 TL film during the growth significantly raises the transition temperature (TC), which is attributed to a reduced screening effect and a more balanced electron and hole carrier density. Our results indicate a CDW formation mechanism consistent with the excitonic insulator phase in low dimensional HfTe2 and open up opportunity for realization of novel quantum states based on exciton condensation. |
| format | Preprint |
| id |
arxiv_https___arxiv_org_abs_2401_13886 |
| institution | arXiv |
| publishDate | 2024 |
| record_format | arxiv |
| spellingShingle | Observation of possible excitonic charge density waves and metal-insulator transitions in atomically thin semimetals Gao, Qiang Chan, Yang-hao Jiao, Pengfei Chen, Haiyang Yin, Shuaishuai Tangprapha, Kanjanaporn Yang, Yichen Li, Xiaolong Liu, Zhengtai Shen, Dawei Jiang, Shengwei Chen, Peng Mesoscale and Nanoscale Physics Charge density wave (CDW) is a collective quantum phenomenon with a charge modulation in solids1-2. Condensation of electron and hole pairs with finite momentum will lead to such an ordered state3-7. However, lattice symmetry breaking manifested as the softening of phonon modes can occur simultaneously, which makes it difficult to disentangle the origin of the transition8-14. Here, we report a condensed phase in low dimensional HfTe2, whereas angle-resolved photoemission spectroscopy (ARPES) measurements show a metal-insulator transition by lowering the temperature in single triatomic layer (TL) HfTe2. A full gap opening, renormalization of the bands, and emergence of replica bands at the M point are observed in the low temperatures, indicating formation of a CDW in the ground state.Raman spectroscopy shows no sign of lattice distortion within the detection limit. The results are corroborated by first-principles calculations, demonstrating the electronic origin of the CDW. By adding more layers, the phase transition is suppressed and completely destroyed at 3 TL because of the increased screening around the Fermi surface. Interestingly, a small amount of electron doping in 1 TL film during the growth significantly raises the transition temperature (TC), which is attributed to a reduced screening effect and a more balanced electron and hole carrier density. Our results indicate a CDW formation mechanism consistent with the excitonic insulator phase in low dimensional HfTe2 and open up opportunity for realization of novel quantum states based on exciton condensation. |
| title | Observation of possible excitonic charge density waves and metal-insulator transitions in atomically thin semimetals |
| topic | Mesoscale and Nanoscale Physics |
| url | https://arxiv.org/abs/2401.13886 |