Fig. 2: Demonstration of MAHAEM for FeSe.
a Topography of FeSe showing the type of defects (Fe-atom vacancies) used for analysis. The x- and y-axes are along top Se–Se atoms. Inset shows the differential conductance spectrum recorded at a point on superconducting FeSe. The dashed rectangle represents the energy limits of the high-resolution dI/dV maps used herein for ρ−(q, E) analysis. b Fermi surface of FeSe showing the scattering between hole-pocket α and electron-pocket ε with scattering vector p1, which is the subject of study. The delta pocket is predicted in LDA calculations, hence it is shown dim in the image, but is now reported not to exist in reality6,38. Due to the orbital content, the scattering between quasi-parallel Fermi surfaces would be strongly suppressed in this orbitally selective material6. c \(\rho _{{\mathrm{MA}}}^ - ({\mathbf{q}},E = 1.05\,{\mathrm{meV}})\) calculated using Eq. (9) for a FOV containing 17 Fe-vacancies. The circle denotes the region where the \(\alpha \to {\it{\varepsilon }}\) scattering occurs and we integrate the \(\rho _{{\mathrm{MA}}}^ - ({\mathbf{q}},E)\) over the q in this region. Black crosses denote the Bragg peaks. d The integrated \(\rho _{{\mathrm{MA}}}^ - (E)\) (dots, black) from our MAHAEM analysis of FeSe compare to the theoretical predictions from an accurate band- and gap-structure model of FeSe for s++ (solid, pink) and s± (solid, black) superconducting energy gap symmetry, and to measured \(\rho _{{\mathrm{single}}}^{ - {\mathrm{Exp}}}(E)\) (crosses, black) from single impurity analysis as reported in ref. 6. Clearly, the single atom \(\rho _{{\mathrm{single}}}^{ - {\mathrm{Exp}}}(E)\) and the MAHAEM \(\rho _{{\mathrm{MA}}}^ - (E)\) are in good agreement. Note that the 2D plots may show both red and blue colors due to non-ideal nature of real experimental data. However, subsequent to the integration over relevant q-space region, the \(\rho _{{\mathrm{MA}}}^ - (E)\) is well defined as demonstrated here.
