Toward one-band superconductivity in MgB2

TL;DR

This paper investigates how impurity-induced lattice distortions in MgB2 can lead to interband scattering, providing a test for the two-gap superconductivity model through specific isoelectronic codoping strategies.

Contribution

It demonstrates theoretically that certain impurities can cause significant lattice distortions, enabling measurable interband scattering in MgB2, which was previously thought negligible.

Findings

Impurities can induce lattice distortions leading to interband scattering.

Isoelectronic codoping with Al and Na can test the two-gap model.

Theoretical predictions suggest measurable effects in MgB2 with specific impurities.

Abstract

The two-gap model for superconductivity in MgB2 predicts that interband impurity scattering should be pair breaking, reducing the critical temperature. This is perhaps the only prediction of the model that has not been confirmed experimentally. It was previously shown theoretically that common substitutional impurities lead to negligible interband scattering - if the lattice is assumed not to distort. Here we report theoretical results showing that certain impurities can indeed produce lattice distortions sufficiently large to create measurable interband scattering. On this basis, we predict that isoelectronic codoping with Al and Na will provide a decisive test of the two-gap model.