2021/03/09 by Ryosuke Akashi, Ryotaro Arita, Chao Zhang +4
Chemistry · Materials Science · Physics and Astronomy · #Chemistry #Condensed matter physics #Crystallography #Halide #Halogen #Inorganic Chemistry and Materials #Inorganic chemistry #Iron-based superconductors research #Lattice vibration #Materials science #Pairing #Phonon #Physics #Rare-earth and actinide compounds #Superconductivity #Yttrium #cond-mat.mtrl-sci #cond-mat.supr-con
paper · pdf · doi:10.1103/physrevb.103.134517
published as Phys. Rev. B 103, 134517 (2021) · 13 pages, 9 figures, 5 tables
arxiv created 2021/03/09 · openalex created_date 2021/03/15 · openalex publication_date 2021/04/29 · arxiv updated 2021/05/05 · openalex updated_date 2026/08/05
We perform a thorough first-principles study on superconductivity in yttrium carbide halide Y2X2C2 (X=Cl, Br, I) whose maximum transition temperature (Tc) amounts to \ensuremath∼10 K. A detailed analysis on the optimized crystal structures reveals that the Y2C2 blocks are compressed uniaxially upon the halogen substitution from Cl, Br to I, contrary to the monotonic expansion of the lattice vectors. With a nonempirical method based on the density functional theory for superconductors within the conventional phonon mechanism, we successfully reproduce the halogen dependence of Tc. An anomalously enhanced coupling of one C2 libration mode is observed in Y2I2C2, which implies a possible departure from the conventional pairing picture. Utilizing the Wannier representation of the electron-phonon coupling, we show that the halogen electronic orbitals and ionic vibrations scarcely contribute to the superconducting pairing. The halogen dependence of this system is hence an indirect effect of the halogen ions through the uniaxial compressive force on the superconducting Y2C2 blocks. We thus establish a quantitatively reliable picture of the superconducting physics of this system, extracting a unique effect of the atomic substitution which is potentially applicable to other superconductors.