High-Pressure Study Of The Anomalous Rare-Earth Ternaries Eu1.2mo6s8 And Eu1.2mo6se8

The two anomalous rare-earth ternaries Eu/sub 1.2/Mo/sub 6/S/sub 8/ and Eu/sub 1.2/Mo/sub 6/Se/sub 8/ are investigated both resistively and magnetically under hydrostatic pressure up to approx.18 kbar. Superconductivity with an onset temperature approx.11 K was observed abruptly at pressure above approx.7 kbar in Eu/sub 1.2/Mo/sub 6/S/sub 8/. However, no superconductivity was detected in Eu/sub 1.2/Mo/sub 6/Se/sub 8/ down to 1.2 K and up to 18 kbar. Several possibilities are discussed and contrasted.