T c as a Function of Electron Doping in Mg10B2 Using Sc for Mg Substitution

Abstract

We have studied the variation of superconducting critical temperature Tc as a function of electron doping in the Mg10B2 system using Sc for Mg substitution. The critical temperature in the10B isotope substituted system Mg1−xScx10B2 increases by increasing the scandium content x in the range 0<x<0.012 up to 41.4 K, while the Tc of the natural boron system Mg1−xScxB2 is nearly constant. The overall difference of Tc in Mg1−xScxB2 as function of x between the natural B and 10B isotope system seems to indicate that the isotope effect shows large variations with electron doping as expected for the Tc enhancement driven by a shape resonance.