ANDREEV REFLECTION AND PROXIMITY EFFECT I N HG0.8PB0.2BA2CU3O8- ABNORMALLY QUICK INCREASE IN DELTA(P)(DELTA CERAMIC UNDER PRESSURE )

The experiments on Andreev reflection for the Ag/Hg1223 junctions have revealed that the energy gap Delta approximate to 42meV of this compo und Increases with pressure much more steeply than the critical temper ature T-c (d Delta / dP = 0.43 +/- 0.03 meV/kbar, dT(c)/dP = = 0.28 +/ - 0.04 K/kbar). The 2 Delta/kT(c) ratio is thus increased from 7.3 to 8 at P = 11 kbar. As is known, the conventional BCS type superconducto rs behave quite inverse way, if the pressure cause's an increase in ph onon Frequencies the 2 Delta/kT(c) ratio decreases.