Symmetry-breaking orbital anisotropy observed for detwinned Ba(Fe1-xCox)2As2 above the spin density wave transition
By M. Yi, D. Lu, J. Chu, J. Analytis, A. P. Sorini, A. Kemper, B. Moritz, S. Mo, R. Moore, M. Hashimoto and 5 more. Proceedings of the National Academy of Sciences of the United States of America, 2010
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Nematicity, defined as broken rotational symmetry, has recently been observed in competing phases proximate to the superconducting phase in the cuprate high-temperature superconductors. Similarly, the new iron-based high-temperature superconductors exhibit a tetragonal-to-orthorhombic structural transition (i.e., a broken C4 symmetry) that either precedes or is coincident with a collinear spin density wave (SDW) transition in undoped parent compounds, and superconductivity arises when both transitions are suppressed via doping. Evidence for strong in-plane anisotropy in the SDW state in this family of compounds has been reported by neutron scattering, scanning tunneling microscopy, and transport measurements. Here, we present an angle-resolved photoemission spectroscopy study of detwinned single crystals of a representative family of electron-doped iron-arsenide superconductors, Ba(Fe1-xCox)2As2 in the underdoped region. The crystals were detwinned via application of in-plane uniaxial stress, enabling measurements of single domain electronic structure in the orthorhombic state. At low temperatures, our results clearly demonstrate an in-plane electronic anisotropy characterized by a large energy splitting of two orthogonal bands with dominant dxz and dyz character, which is consistent with anisotropy observed by other probes. For compositions x > 0, for which the structural transition (TS) precedes the magnetic transition (TSDW), an anisotropic splitting is observed to develop above TSDW, indicating that it is specifically associated with TS. For unstressed crystals, the band splitting is observed close to TS, whereas for stressed crystals, the splitting is observed to considerably higher temperatures, revealing the presence of a surprisingly large in-plane nematic susceptibility in the electronic structure.
Subfields: Condensed Matter Physics, Electronic, Optical and Magnetic Materials
View Paper: https://www.semanticscholar.org/paper/33e60a53b2665c797ebb2e81ef9b4dfd6be4fc95
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Citations in the corpus
- Nematic order in iron superconductors - who is in the driver's seat? (2013, background): “• Charge orbital order – the occupations nxz and nyz (and on-site energies) of the dxz and dyz Fe-orbitals become different [11].”
- Superconductivity in iron compounds (2011, neutral): “Yi et al. (2011), in an ARPES study of Co doped BaFe2As2 single crystals under uniaxial stress (which of course intrinsically provides symmetry breaking) to detwin the orthorhombic state, found electronic anisotropy well above the structural phase transition.”
- Iron-based high transition temperature superconductors (2014, background): “10(i)) as well, showing that it generally occurs in different compounds [130].”
- A Quantum Critical Point Lying Beneath the Superconducting Dome in Iron Pnictides (2013, background): “[18] Yi M, Lu D, Chu J-H, Analytis JG, Sorini AP et al.”
- Angle-resolved photoemission studies of quantum materials (2020, positive): “…applied in-situ to detwin the sample (Chu et al., 2010), revealing a 30-120 meV band shift between the otherwise degenerate dyz and dxz components near the zone boundary in the nematic phase (Kim et al., 2011b; Shimojima et al., 2014; Watson et al., 2019; Yi et al., 2011; Zhang et al., 2012a).”
- Magnetism and its microscopic origin in iron-based high-temperature superconductors (2012, neutral): “ARPES experiments on the same materials [113] reported a dxz and dyz band splitting (Fig.”