Phonon dispersions and Fermi surfaces nesting explaining the variety of charge ordering in titanium-oxypnictides superconductors

Abstract

There has been a puzzle between experiments and theoretical predictions on the charge ordering of layered titanium-oxypnictides superconductors. Unconventional mechanisms to explain this discrepancy have been argued so far, even affecting the understanding of superconductivity on the compound. We provide a new theoretical prediction, by which the discrepancy itself is resolved without any complicated unconventional explanation. Phonon dispersions and changes of nesting vectors in Fermi surfaces are clarified to lead to the variety of superlattice structures even for the common crystal structures when without CDW, including orthorhombic $2\times 2\times 1$ one for BaTi${}_2$As${}_2$O, which has not yet been explained successfully so far, being different from tetragonal $\sqrt{2}\times \sqrt{2}\times 1$ for BaTi${}_2$Sb${}_2$O and BaTi${}_2$Bi${}_2$O. The electronic structure analysis can naturally explain experimental observations about CDW including most latest ones without any cramped unconventional mechanisms.

Scientific Reports accepted

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Cited by in corpus (9)

• High-$T_c$ superconducting hydrides formed by LaH${}_{24}$ and YH${}_{24}$ cage structures as basic blocks
• Double stage nematic bond-ordering above double stripe magnetism: application to BaTi${}_2$Sb${}_2$O
• A computational scheme to evaluate Hamaker constants of molecules with practical size and anisotropy
• $\mathbf{Ab}\mathbf{initio}$ search of polymer crystals with high thermal conductivity
• Application of canonical augmentation to the atomic substitution problem
• Nematic transition and highly two-dimensional superconductivity in BaTi${}_2$Bi${}_2$O revealed by ${}^{209}$Bi-nuclear magnetic resonance/nuclear quadrupole resonance measurements
• Commensurate lattice distortion in the layered titanium oxypnictides Na${}_2$Ti${}_{2}P{n}_2$O ($Pn=$ As, Sb) determined by X-ray diffraction
• Exotic phase transition and superconductivity in layered titanium-oxypnictides implied by a computational phonon analysis
• Revealing the hidden order in BaTi2As2O via nuclear magnetic resonance