Real-space Observation of Unidirectional Charge Density Wave and Complex Structural Modulation in the Pnictide Superconductor Ba$_{1-x}$Sr$_x$Ni$_2$As$_2$
| Autor: | Qin, Tian, Zhong, Ruixia, Cao, Weizheng, Shen, Shiwei, Wen, Chenhaoping, Qi, Yanpeng, Yan, Shichao |
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| Rok vydání: | 2022 |
| Předmět: | |
| Zdroj: | Nano Letters 23, 2958-2963 (2023) |
| Druh dokumentu: | Working Paper |
| DOI: | 10.1021/acs.nanolett.3c00323 |
| Popis: | Here we use low-temperature and variable-temperature scanning tunneling microscopy to study the pnictide superconductor, Ba$_{1-x}$Sr$_x$Ni$_2$As$_2$. In the low-temperature phase (triclinic phase) of BaNi$_2$As$_2$, we observe the unidirectional charge density wave (CDW) with $Q$ = 1/3 on both the Ba and NiAs surfaces. On the NiAs surface of the triclinic BaNi$_2$As$_2$, there are structural-modulation-induced chain-like superstructures with distinct periodicities. In the high-temperature phase (tetragonal phase) of BaNi$_2$As$_2$, the NiAs surface appears as the periodic 1 by 2 superstructure. Interestingly, in the triclinic phase of Ba$_{0.5}$Sr$_{0.5}$Ni$_2$As$_2$, the unidirectional CDW is suppressed on both the Ba/Sr and NiAs surfaces, and the Sr substitution stabilizes the periodic 1 by 2 superstructure on the NiAs surface, which enhance the superconductivity in Ba$_{0.5}$Sr$_{0.5}$Ni$_2$As$_2$. Our results provide important microscopic insights for the interplay among the unidirectional CDW, structural modulation, and superconductivity in this class of pnictide superconductors. Comment: 15 pages, 4 figures |
| Databáze: | arXiv |
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