High Pressure Superconducting Behavior of the Stage-1 Alkali Metal-Graphite Intercalation Compounds RbC sub 8 and CsC sub 8

摘要

We have performed measurements of the pressure dependence of the superconducting transition temperature T/sub c/ of the stage-1 graphite intercalation compounds RbC sub 8 and CsC sub 8 as a function of hydrostatic pressure P less than or equal to 2.2 GPa. RbC sub 8 is nonsuperconducting to temperatures T greater than or equal to 0.07 degrees K at P = 0 and to T greater than or equal to 1.3 degrees K for P less than or equal to 2.2 GPa. However, T/sub c/'s greater than or equal to 0.25 degrees K were detected at P < 0.09 GPa. A superconducting transition was also found for CsC sub 8 at P = 0 with an onset temperature T degrees approx. = 0.09 degrees K. Our high pressure results suggest that pressure-induced phase transitions may be present in RbC sub 8 at P < 0.09 GPa and in CsC sub 8 at P > 0.8 GPa. (ERA citation 10:007162)