Shiba multiplets due to Mn impurities in MgB_2

TL;DR

This paper investigates how magnetic Mn impurities induce multiple Shiba states in MgB_2, revealing complex spectral features overlooked by simpler models, with implications for understanding magnetic effects in superconductors.

Contribution

It introduces a detailed model accounting for Mn d-shell structure, predicting multiple Shiba multiplets in MgB_2, advancing the understanding of magnetic impurity effects in two-band superconductors.

Findings

Multiple Shiba states appear near Mn impurities in MgB_2

Complex multiplet structures are revealed in the tunneling spectra

Previous simplistic models missed these multiplet features

Abstract

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