Metallicity of Ca2Cu6P5 with Single and Double Copper-Pnictide Layers
| Autor: | Li, Li, Parker, David, Chi, Miaofang, Tsoi, Georgiy M., Vohra, Yogesh K., Sefat, Athena S. |
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| Rok vydání: | 2015 |
| Předmět: | |
| Zdroj: | Phys. Rev. B 94, 134510 (2016) |
| Druh dokumentu: | Working Paper |
| DOI: | 10.1103/PhysRevB.94.134510 |
| Popis: | We report thermodynamic and transport properties, and also theoretical calculations, for Cu-based compound Ca2Cu6P5 and compare with CaCu(2-x)P2. Both materials have layers of edge-sharing copper pnictide tetrahedral CuP4, similar to Fe-As and Fe-Se layers (with FeAs4, FeSe4) in the iron-based superconductors. Despite the presence of this similar transition-metal pnictide layer, we find that both Ca2Cu6P5 and CaCu(2-x)P2 have temperature-independent magnetic susceptibility and show metallic behavior with no evidence of either magnetic ordering or superconductivity down to 1.8 K. CaCu(2-x)P2 is slightly off-stoichiometric, with delta = 0.14. Theoretical calculations suggest that unlike Fe 3d-based magnetic materials with a large density of states (DOS) at the Fermi surface, Cu have comparatively low DOS, with the majority of the 3d spectral weight located well below Fermi level. The room-temperature resistivity value of Ca2Cu6P5 is only 9 micro ohm-cm, due to a substantial plasma frequency and an inferred electron-phonon coupling lambda of 0.073 (significantly smaller than that of metallic Cu). Also, microscopy result shows that Cu-Cu distance along the c-axis within the double layers can be very short (2.5 A), even shorter than metallic elemental copper bond (2.56 A). The value of dp over dT for CaCu(2-x)P2 at 300 K is approximately three times larger than in Ca2Cu6P5, which suggests the likelihood of stronger electron-phonon coupling. This study shows that the details of Cu-P layers and bonding are important for their transport characteristics. In addition, it emphasizes the remarkable character of the DOS of '122' iron-based materials, despite much structural similarities. Comment: 13 pages, 5 figures |
| Databáze: | arXiv |
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