Is Delta_{pi}-gap-only superconductivity possible in Mg_{1-x}Al_{x}B_{2} and Mg(B_{1-y}C_{y})_{2} alloys?

TL;DR

This study uses density-functional calculations to analyze how impurity concentration affects sigma- and pi-band holes in Mg_{1-x}Al_{x}B_{2} and Mg(B_{1-y}C_{y})_{2} alloys, providing insights into the possibility of delta_{pi}-gap-only superconductivity.

Contribution

It offers a detailed k-resolved analysis of band hole loss in these alloys, linking electronic structure changes to superconductivity implications.

Findings

Qualitative agreement with experimental hole loss profiles

Implications for superconductivity in Mg_{1-x}Al_{x}B_{2} and Mg(B_{1-y}C_{y})_{2}

Insights into the feasibility of delta_{pi}-gap-only superconductivity

Abstract

Using density-functional-based method, we study the k-resolved sigma- and pi-band holes in Mg_{1-x}Al_{x}B_{2} and Mg(B_{1-y}C_{y})_{2} alloys. We find that the calculated profiles of the loss of sigma- and pi-band holes in these two systems as a function of impurity concentration are in qualitative agreement with experiments, as expected. We also describe its implications vis-a-vis superconductivity in Mg_{1-x}Al_{x}B_{2} and Mg(B_{1-y}C_{y})_{2}.