High-pressure study on MgB 2

The hydrostatic pressure effect on the newly discovered superconductor ${\mathrm{MgB}}_{2}$ has been determined. The transition temperature ${T}_{c}$ was found to decrease linearly at a large rate of $\ensuremath{-}1.6 \mathrm{K}/\mathrm{G}\mathrm{P}\mathrm{a},$ in good quantitative agreement with the ensuing calculated value of $\ensuremath{-}1.4 \mathrm{K}/\mathrm{G}\mathrm{P}\mathrm{a}$ within the BCS framework by Loa and Syassen, using the full-potential linearized augmented plane-wave method. The relative pressure coefficient $d\mathrm{ln}{T}_{c}/dp$ for ${\mathrm{MgB}}_{2}$ also falls between the known values for conventional $\mathrm{sp}$ and d superconductors. The observation, therefore, suggests that electron-phonon interactions play a significant role in the superconductivity of the compound.