A catastrophic charge density wave in BaFe$_2$Al$_9$
| Autor: | Meier, William R., Chakoumakos, Bryan C., Okamoto, Satoshi, McGuire, Michael A., Hermann, Raphaël P., Samolyuk, German D., Gao, Shang, Zhang, Qiang, Stone, Matthew B., Christianson, Andrew D., Sales, Brian C. |
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| Rok vydání: | 2021 |
| Předmět: | |
| Druh dokumentu: | Working Paper |
| DOI: | 10.1021/acs.chemmater.1c00005 |
| Popis: | Charge density waves (CDW) are modulations of the electron density and the atomic lattice that develop in some crystalline materials at low temperature. We report an unusual example of a CDW in BaFe$_2$Al$_9$ below 100 K. In contrast to the canonical CDW phase transition, temperature dependent physical properties of single crystals reveal a first-order phase transition. This is accompanied by a discontinuous change in the size of the crystal lattice. In fact, this large strain has catastrophic consequences for the crystals causing them to physically shatter. Single crystal x-ray diffraction reveals super-lattice peaks in the low-temperature phase signaling the development of a CDW lattice modulation. No similar low-temperature transitions are observed in BaCo$_2$Al$_9$. Electronic structure calculations provide one hint to the different behavior of these two compounds; the d-orbital states in the Fe compound are not completely filled. Iron compounds are renowned for their magnetism and partly filled d-states play a key role. It is therefore surprising that BaFe$_2$Al$_9$ develops a structural modulation instead at low temperature instead of magnetic order. Comment: 34 pages, 8 figures Edits to text as well as figures 2 and 5. Added neutron diffraction (Fig. 6) |
| Databáze: | arXiv |
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