Dependence of the superconducting transition temperature of MgB sub(2) on pressure to 20 GPa

The dependence of T sub(c) on nearly hydrostatic pressure has been measured for an isotopically pure ( super(11)B) MgB sub(2) sample in a helium-loaded diamond-anvil-cell to nearly 20 GPa. T sub(c) decreases monotonically with pressure from 39.1 K at ambient pressure to 20.9 K at 19.2 GPa. The initial dependence is the same as that obtained earlier (dT sub(c)/dP[asymptotically equal to]-1.11(2) K/GPa) on the same sample in a He-gas apparatus to 0.7 GPa. The observed pressure dependence T sub(c)(P) to 20 GPa can be readily described in terms of simple lattice stiffening within standard phonon-mediated BCS superconductivity. copyright 2001 Elsevier Science B.V. All rights reserved.