The Tc amplification by quantum interference effects in diborides

TL;DR

This paper models how quantum interference effects amplify the superconducting transition temperature (Tc) in diborides, showing significant enhancement from MgB2 to AlMgB4 due to interband coupling.

Contribution

It introduces a model applying two-channel superconductivity to diborides, demonstrating how quantum interference effects substantially increase Tc in these materials.

Findings

Quantum interference amplifies Tc by 1.5 in MgB2.

Amplification reaches about 100 in AlMgB4.

Interband coupling varies with composition x.

Abstract

The model of two (s and p) channel superconductivity known to be necessary to explain the superconductivity in MgB2 has been applied to the Al1-xMgxB2 diborides by tuning x from MgB2 to AlMgB4. The evolution of the interband coupling parameter (probing the strength of the interchannel pairing due to quantum interference effects) and the two gaps in the s and p channel as a function of x have been calculated. While in MgB2 the quantum interference effects give an amplification of Tc by a factor of 1.5 in comparison with the dominant intra s band single channel pairing, in AlMgB4 the amplification is about 100, in comparison with the dominant intra p band single channel pairing.