Fig. 6: Utility of phase-sensitive QPI.
From: Dictionary learning in Fourier-transform scanning tunneling spectroscopy
a Differential conductance map at ω = −10 meV for an optimally doped NaFe1−xCoxAs sample (x = 0.02), over a 250 nm × 250 nm2 field of view with T = 5.9 K, I = 200 pA, and Vset = −50 meV. b Recovered kernel, \(\hat{{\mathcal{A}}}\), from the conductance map in a. c Fourier transform of the recovered kernel. d \({\hat{{\mathcal{A}}}}^{-}(\omega)\), computed from the recovered kernels. The large and constant sign of the response is an indication of s± pairing. (inset) theoretical expectations for s± and s++ pairing e Spatially averaged differential conductance from the same area as a function of energy, revealing the superconducting gap 2Δ = 11 meV. The STM spectroscopy maps have been drift corrected as outlined in Supplementary Note 7.
