Commensurate lattice distortion in the layered titanium oxypnictides Na${}_2$Ti${}_{2}P{n}_2$O ($Pn=$ As, Sb) determined by X-ray diffraction

Abstract

We report single crystal X-ray diffraction measurements on Na${}_2$Ti${}_{2}P{n}_2$O ($Pn$ = As, Sb) which reveal a charge superstructure that appears below the density wave transitions previously observed in bulk data. From symmetry-constrained structure refinements we establish that the associated distortion mode can be described by two propagation vectors, ${\mathbf{q}}_1=(1/2,0,l)$ and ${\mathbf{q}}_2=(0,1/2,l)$, with $l=0$ (Sb) or $l=1/2$ (As), and primarily involves in-plane displacements of the Ti atoms perpendicular to the Ti--O bonds. The results provide direct evidence for phonon-assisted charge density wave order in Na${}_2$Ti${}_{2}P{n}_2$O and identify a proximate ordered phase that could compete with superconductivity in doped BaTi${}_2$Sb${}_2$O.

References in corpus (13)

• Direct observation of competition between superconductivity and charge density wave order in YBa2Cu3Oy
• Charge density wave fluctuations in La2-xSrxCuO4 and their competition with superconductivity
• Ba1-xNaxTi2Sb2O (0.0 <= x <= 0.33): A Layered Titanium-based Pnictide Oxide Superconductor
• Electronic structure, disconnected Fermi surfaces and antiferromagnetism in the layered pnictide superconductor Na${}_x$Ba${}_{1-x}$Ti${}_2$Sb${}_2$O
• S wave superconductivity in newly discovered superconductor BaTi${}_2$Sb${}_2$O revealed by ${}^{121/123}$Sb-NMR/Nuclear Quadrupole Resonance measurements
• Superconductivity, charge- or spin-density wave, and metal-nonmetal transition in BaTi${}_2$(Sb${}_{1-x}$Bi${}_x$)${}_2$O
• Electron-phonon superconductivity and charge density wave instability in the layered titanium-based pnictide BaTi${}_2$Sb${}_2$O
• Intra-unit-cell nematic charge order in the titanium-oxypnictide family of superconductors
• Phonon dispersions and Fermi surfaces nesting explaining the variety of charge ordering in titanium-oxypnictides superconductors
• Formation of the density wave energy gap in Na${}_2$Ti${}_2$Sb${}_2$O: an optical spectroscopy study
• Superconductivity in titanium-based pnictide oxide compounds
• Photoemission study of the electronic structure and charge density waves of Na2Ti2Sb2O
• New phase transition in Na${}_2$Ti${}_2$As${}_2$O revealed by Raman scattering

Cited by in corpus (5)

• Weak metal-metal transition in the vanadium oxytelluride Rb${}_{1-\delta }$V${}_2$Te${}_2$O
• 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
• Absence of magnetism in the superconductor Ba2Ti2Fe2As4O: Insights from inelastic neutron scattering measurements and ab initio calculations of phonon spectra
• Theory for doping trends in titanium oxypnictide superconductors