Quasiparticle Scattering Interference in (K,Tl)FexSe2 Superconductors

Abstract

We model the quasiparticle interference (QPI) pattern in the recently discovered (K,Tl)Fe_xSe2 superconductors. We show in the superconducting state that, due to the absence of hole pockets at the Brillouin zone center, the quasiparticle scattering occurs around the momentum transfer q=(0,0) and (\pm π, \pm π) between electron pockets located at the zone boundary. More importantly, although both d_{x^2-y^2}-wave and s-wave pairing symmetry lead to nodeless quasiparticle excitations, distinct QPI features are predicted between both types of pairing symmetry. In the presence of a nonmagnetic impurity scattering, the QPI exhibits strongest scattering with q=(\pm π, \pm π) for the d_{x^2-y^2}-wave pairing symmetry; while the strongest scattering exhibits a ring-like structure centered around both q=(0,0) and (\pm π, \pm π) for the isotropic s-wave pairing symmetry. A unique QPI pattern has also been predicted due to a local pair-potential-type impurity scattering. The significant contrast in the QPI pattern between the d_{x^2-y^2}-wave and the isotropic s-wave pairing symmetry can be used to probe the pairing symmetry within the Fourier-transform STM technique.

4+ pages, 3 embedded eps figures

References in corpus (10)

• Heavily electron-doped electronic structure and isotropic superconducting gap in AxFe2Se2 (A=K,Cs)
• Fe-based high temperature superconductivity with Tc=31K bordering an insulating antiferromagnet in (Tl,K)FexSe2 Crystals
• d-wave pairing from spin fluctuations in the KxFe{2-y}Se2 superconductors
• Mott transition in Modulated Lattices and Parent Insulator of (K,Tl)yFexSe2 Superconductors
• Stripes, spin resonance and $d_{x^2-y^2}-$pairing symmetry in FeSe-based layered superconductors
• Electronic and magnetic structures of ternary iron selenides AFe${}_2$Se${}_2$ (A=K, Cs, or Tl)
• Electronic Structure, Topological Phase Transitions and Superconductivity in (K,Cs)xFe2Se2
• Density Functional Study of the Over-Doped Iron Chalcogenide: TlFe${}_2$Se${}_2$ with ThCr${}_2$Si${}_2$ structure
• Electronic Structure and Mott Localization in Iron Deficient TlFe${}_{1.5}$Se${}_2$ with Superstructures
• A minimum single-band model for low-energy excitations in superconducting K${}_x$Fe${}_2$Se${}_2$