Fig. 1. Shiba states of single Mn adatoms on Nb(110).

a dI/dV spectra obtained on bare Nb(110) (black) and over a Mn adatom (blue). Red and green vertical lines mark the positions of the coherence peaks ±(Δ_Nb + Δ_tip) and the tip gap Δ_tip, respectively. b Magnification of the spectra shown in panel a. The coherence peaks and the two peaks with the largest intensity are left out for the sake of visibility. Shiba states are labeled and marked by arrows. c Overview STM image of the Mn/Nb(110) sample, where bright protrusions are single Mn adatoms and black depressions correspond to residual oxygen. The white scale bar has a length of 3 nm. (V_bias = 100 mV and I = 200 pA). d STM image of a single Mn adatom, which was used for recording the spectra in a and b, as well as for the dI/dV maps in f–i. The white scale bar has a length of 500 pm and the red arrows point along two high symmetry directions $\left[1\overline{1}0\right]$ and [001] of the Nb(110) surface. The directions also apply to panels f–i and k–n. e 3D rendered illustration of the position of the single Mn adatom (black sphere) with respect to the Nb substrate atoms (yellow spheres), including the high-symmetry directions indicated by blue arrows with their nomenclature. f–i dI/dV maps measured at the given bias voltages of the Shiba states marked in a and b and in the area of d in the vicinity of the single Mn adatom. The dI/dV maps taken at the Shiba peaks on the positive bias side are shown in Supplementary Fig. 5. j Calculated LDOS inside the superconducting gap convoluted with the DOS of the superconducting tip (${\pm \mathrm{\Delta }}_{\mathrm{tip}}=1.43$ mV) at the position of the Mn adatom (blue) and on the bare superconductor (black). k–n Calculated two-dimensional maps of the LDOS at the bias voltages indicated in the figures. The white scale bar has a length of 500 pm. Red circles in f–i and k–n highlight the position of the adatom.