Raman scattering in superconducting NdO_1−xF_xBiS₂crystals

Abstract

The recently discovered layered BiS 2 -based superconductors have attracted a great deal of interest due to their structural similarity to cuprate and iron-pnictide

Weak phonon-mediated pairing in BiS2 superconductor from first principles

“…Its parent compound is insulating and becomes superconducting upon doping, which raises the Fermi level in a rigid band fashion [4]. Various variations of this composition have been attempted, of which the most studied have been the replacement of lanthanum with a different lanthanide [7][8][9][10][11][12].…”

High-pressure effects on La(O,F)BiS2 single crystal using diamond anvil cell with dual-probe diamond electrodes

“…At ambient pressure, two peaks are observed at 70 and 123 cm −1 , which correspond to the Raman active A 1g symmetric mode originating from the in-plane vibrations of Bi and S atoms. 30) According to the Raman investigation of Nd(O,F)BiS 2 , 31) an electron-phonon coupling constant λ ∼ 0.16 driven from the A 1g mode is not sufficient to explain their T c , suggesting an unconventional pairing mechanism at ambient pressure. The pattern of the vibration modes is completely changed at 0.9 GPa, indicating a pressure-induced structural phase transition.…”

Electrical Transport Measurements on Layered La(O,F)BiS2 under Extremely High Pressure

“…The positions of the corresponding peaks were slightly shifted to a higher wavenumber at 1.2 GPa. As reported in precise Raman analysis for La(O,F)BiS2 single crystal [19], the original A1g mode disappeared, and Raman spectroscopy is often used to discuss the structure and vibration modes in the BiS 2 -based compounds [19,34,35]. Figure 3a displays the Raman spectra of the La(O,F)BiS 2 single crystal up to 83 GPa from the ambient pressure.…”

“…From the Ginzburg−Landau (GL) formula, Bc2(0) = Φ0/2πξ(0) 2 , where Φ0 is the fluxoid and the coherence length at zero temperature ξ(0) is estimated to be 11.2 nm. Raman spectroscopy is often used to discuss the structure and vibration modes in the BiS2-based compounds [19,34,35]. Figure 3a displays the Raman spectra of the La(O,F)BiS2 single crystal up to 83 GPa from the ambient pressure.…”