Intra-unit-cell nematic charge order in the titanium-oxypnictide family of superconductors

Abstract

Understanding the role played by broken symmetry states such as charge, spin, and orbital orders in the mechanism of emergent properties such as high-temperature superconductivity (HTSC) is a major current topic in materials research. That the order may be within one unit cell, such as nematic, was only recently considered theoretically, but its observation in the iron-pnictide and doped cuprate superconductors places it at the forefront of current research. Here we show that the recently discovered BaTi${}_2$Sb${}_2$O superconductor and its "parent" compound BaTi${}_2$As${}_2$O form a symmetry-breaking nematic ground state that can be naturally explained as an intra-unit-cell charge order with $d$-wave symmetry, pointing to the ubiquity of the phenomenon. These findings, together with the key structural features in these materials being intermediate between the cuprate and iron-pnictide HTSC materials, render the titanium oxypnictides an important new material system to understand the nature of nematic order and its relationship to superconductivity.

7 pages, 5 figures

References in corpus (7)

• Direct observation of competition between superconductivity and charge density wave order in YBa2Cu3Oy
• Direct phase-sensitive identification of a d-form factor density wave in underdoped cuprates
• 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

Cited by in corpus (8)

• Exploration of new superconductors and functional materials and fabrication of superconducting tapes and wires of iron pnictides
• Diversity of charge orderings in correlated systems
• Phase Competition and Anomalous Thermal Evolution in High-Temperature Superconductors
• Extended Falicov-Kimball model: Exact solution for finite temperatures
• Nematic transition and highly two-dimensional superconductivity in BaTi${}_2$Bi${}_2$O revealed by ${}^{209}$Bi-nuclear magnetic resonance/nuclear quadrupole resonance measurements
• Extended Falicov-Kimball model: Hartree-Fock vs DMFT approach
• Emergent Ising degrees of freedom above double-stripe magnetism
• Magnetism and Correlated Electrons in LaCr${}_2$Ge${}_2$N