High-pressure study onMgB2

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 $-1.6\hspace{0.5em}\mathrm{K}/\mathrm{G}\mathrm{P}\mathrm{a},$ in good quantitative agreement with the ensuing calculated value of $-1.4\hspace{0.5em}\mathrm{K}/\mathrm{G}\mathrm{P}\mathrm{a}$ within the BCS framework by Loa and Syassen, using the full-potential linearized augmented plane-wave method. The relative pressure coefficient $d\ln T_c/dp$ 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.