Browsing by Author "Hu, Chaowei"

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    Absence of ${E}_{2g}$ Nematic Instability and Dominant ${A}_{1g}$ Response in the Kagome Metal ${\mathrm{CsV}}_{3}{\mathrm{Sb}}_{5}$
    (American Physical Society, 2024) Liu, Zhaoyu; Shi, Yue; Jiang, Qianni; Rosenberg, Elliott W.; DeStefano, Jonathan M.; Liu, Jinjin; Hu, Chaowei; Zhao, Yuzhou; Wang, Zhiwei; Yao, Yugui; Graf, David; Dai, Pengcheng; Yang, Jihui; Xu, Xiaodong; Chu, Jiun-Haw
    Ever since the discovery of the charge density wave (CDW) transition in the kagome metal CsV3โขSb5, the nature of its symmetry breaking has been under intense debate. While evidence suggests that the rotational symmetry is already broken at the CDW transition temperature (๐‘‡CDW), an additional electronic nematic instability well below ๐‘‡CDW has been reported based on the diverging elastoresistivity coefficient in the anisotropic channel (๐‘š๐ธ2โข๐‘”). Verifying the existence of a nematic transition below ๐‘‡CDW is not only critical for establishing the correct description of the CDW order parameter, but also important for understanding low-temperature superconductivity. Here, we report elastoresistivity measurements of CsV3โขSb5 using three different techniques probing both isotropic and anisotropic symmetry channels. Contrary to previous reports, we find the anisotropic elastoresistivity coefficient ๐‘š๐ธ2โข๐‘” is temperature independent, except for a step jump at ๐‘‡CDW. The absence of nematic fluctuations is further substantiated by measurements of the elastocaloric effect, which show no enhancement associated with nematic susceptibility. On the other hand, the symmetric elastoresistivity coefficient ๐‘š๐ด1โข๐‘” increases below ๐‘‡CDW, reaching a peak value of 90 at ๐‘‡*=20 K. Our results strongly indicate that the phase transition at ๐‘‡* is not nematic in nature and the previously reported diverging elastoresistivity is due to the contamination from the ๐ด1โข๐‘” channel.
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    Reversible non-volatile electronic switching in a near-room-temperature van der Waals ferromagnet
    (Springer Nature, 2024) Wu, Han; Chen, Lei; Malinowski, Paul; Jang, Bo Gyu; Deng, Qinwen; Scott, Kirsty; Huang, Jianwei; Ruff, Jacob P. C.; He, Yu; Chen, Xiang; Hu, Chaowei; Yue, Ziqin; Oh, Ji Seop; Teng, Xiaokun; Guo, Yucheng; Klemm, Mason; Shi, Chuqiao; Shi, Yue; Setty, Chandan; Werner, Tyler; Hashimoto, Makoto; Lu, Donghui; Yilmaz, Turgut; Vescovo, Elio; Mo, Sung-Kwan; Fedorov, Alexei; Denlinger, Jonathan D.; Xie, Yaofeng; Gao, Bin; Kono, Junichiro; Dai, Pengcheng; Han, Yimo; Xu, Xiaodong; Birgeneau, Robert J.; Zhu, Jian-Xin; da Silva Neto, Eduardo H.; Wu, Liang; Chu, Jiun-Haw; Si, Qimiao; Yi, Ming; Rice Center for Quantum Materials
    Non-volatile phase-change memory devices utilize local heating to toggle between crystalline and amorphous states with distinct electrical properties. Expanding on this kind of switching to two topologically distinct phases requires controlled non-volatile switching between two crystalline phases with distinct symmetries. Here, we report the observation of reversible and non-volatile switching between two stable and closely related crystal structures, with remarkably distinct electronic structures, in the near-room-temperature van der Waals ferromagnet Fe5โˆ’ฮดGeTe2. We show that the switching is enabled by the ordering and disordering of Fe site vacancies that results in distinct crystalline symmetries of the two phases, which can be controlled by a thermal annealing and quenching method. The two phases are distinguished by the presence of topological nodal lines due to the preserved global inversion symmetry in the site-disordered phase, flat bands resulting from quantum destructive interference on a bipartite lattice, and broken inversion symmetry in the site-ordered phase.