Study of pressure effect on the magnetic penetration depth in MgB$_2$

TL;DR

This study investigates how pressure influences the magnetic penetration depth in MgB$_2$, revealing minimal effects compared to cuprates and suggesting electron-phonon interactions as the main factor.

Contribution

It provides experimental data on pressure effects on MgB$_2$'s penetration depth and highlights the dominant role of electron-phonon interactions in this context.

Findings

Pressure causes only slight change in $rac{ riangle \lambda^{-2}}{\lambda^{-2}}$ (~1.5%)

Contrasts with cuprates where pressure significantly affects $\lambda^{-2}$

Electron-phonon interaction primarily explains pressure effects in MgB$_2$

Abstract

A study of the pressure effect on the magnetic penetration depth $\lambda$ in polycrystalline MgB$_{2}$ was performed by measuring the temperature dependence of the magnetization under an applied pressure of 0.15 and 1.13 GPa. We found that $\lambda^{-2}$ at low temperature is only slightly affected by pressure [$\frac{\Delta \lambda^{-2}}{\lambda^{-2}} = 1.5(9)%$], in contrast to cuprate superconductors, where, in the same range of pressure, a very large effect on $\lambda^{-2}$ was found. Theoretical estimates indicate that most of the pressure effect on $\lambda^{-2}$ in MgB$_2$ arises from the electron-phonon interaction.