Shiba multiplets due to Mn impurities in MgB_2

We study the effect of magnetic Mn ions on the two-band superconductor MgB_2, and compute both the total and spin resolved scanning tunneling spectrum in the vicinity of the magnetic impurity. We show that when the internal structure of the Mn ion's $d$-shell is taken into account, multiple Shiba states appear in the spectrum. These multiplets were missed by previous calculations based on simplistic models, and their presence could alter significantly the overall interpretation of local tunneling spectra for a wide range of superconducting hosts and magnetic impurities