Absence of a boron isotope effect in the magnetic penetration depth of MgB$_{2}$

TL;DR

This study investigates the boron isotope effect on the magnetic penetration depth in MgB$_{2}$ and finds no significant isotope effect, indicating an adiabatic superconducting behavior unlike cuprates.

Contribution

It provides experimental evidence that MgB$_{2}$ shows no boron isotope effect on penetration depth, suggesting different superconducting mechanisms from high-temperature cuprates.

Findings

No boron isotope effect on $\lambda(0)$ within experimental error

MgB$_{2}$ is an adiabatic superconductor

Contrasts with oxygen isotope effects in cuprates

Abstract

The magnetic penetration depth $\lambda(0)$ in polycrystalline MgB$_{2}$ for different boron isotopes ($^{10}$B/$^{11}$B) was investigated by transverse field muon spin rotation. No boron isotope effect on the penetration depth $\lambda(0)$ was found within experimental error: $\Delta\lambda(0)/\lambda(0) = -0.8(8)%$, suggesting that MgB$_{2}$ is an adiabatic superconductor. This is in contrast to the substantial oxygen isotope effect on $\lambda(0)$ observed in cuprate high-temperature superconductors.