Experimental confirmation of the low B isotope coefficient in MgB2

TL;DR

This paper experimentally confirms that the B isotope coefficient in MgB2 is low, highlighting unresolved issues in the physics of this superconductor despite accounting for disorder effects.

Contribution

It introduces a procedure that considers disorder effects in evaluating the B isotope coefficient, aligning results with previous findings and questioning existing theoretical explanations.

Findings

Confirmed low B isotope coefficient in MgB2

Disorder effects significantly influence isotope coefficient measurements

Unresolved physics in MgB2 remains despite accounting for disorder

Abstract

Recent investigations have shown that the first proposed explanations of the disagreement between experimental and theoretical value of isotope coefficient in MgB2 need to be reconsidered. Considering that in samples with residual resistivity of few mu-Ohm cm critical temperature variations produced by disorder effects can be comparable with variations due to the isotopic effect, we adopt a procedure in evaluating the B isotope coefficient which take account of these effects, obtaining a value which is in agreement with previous results and then confirming that there is something still unclear in the physics of MgB2.