Hysteresis underlies a large number of phase transitions in solids, giving rise to exotic metastable states that are otherwise inaccessible. Here, we report an unconventional hysteretic transition in a quasi-2D material, EuTe4. By combining transport, photoemission, diffraction, and x-ray absorption measurements, we observed that the hysteresis loop has a temperature width of more than 400 K, setting a record among crystalline solids. The transition has an origin distinct from known mechanisms, lying entirely within the incommensurate charge-density-wave (CDW) phase of EuTe4 with no change in the CDW modulation periodicity. We interpret the hysteresis as an unusual switching of the relative CDW phases in different layers, a phenomenon unique to quasi-2D compounds that is not present in either purely 2D or strongly-coupled 3D systems. Our findings challenge the established theories on metastable states in density wave systems, pushing the boundary of understanding hysteretic transitions in a broken-symmetry state.
@article{arxiv.2106.09774,
title = {Unconventional hysteretic transition in a charge density wave},
author = {B. Q. Lv and Alfred Zong and D. Wu and A. V. Rozhkov and Boris V. Fine and Su-Di Chen and Makoto Hashimoto and Dong-Hui Lu and M. Li and Y. -B. Huang and Jacob P. C. Ruff and Donald A. Walko and Z. H. Chen and Inhui Hwang and Yifan Su and Xiaozhe Shen and Xirui Wang and Fei Han and Hoi Chun Po and Yao Wang and Pablo Jarillo-Herrero and Xijie Wang and Hua Zhou and Cheng-Jun Sun and Haidan Wen and Zhi-Xun Shen and N. L. Wang and Nuh Gedik},
journal= {arXiv preprint arXiv:2106.09774},
year = {2022}
}