Anomalous pressure effect on superconductivity in (Lu1−xScx)5Ir4Si10

Abstract

Abstract Results of pressure effect on the superconducting transition temperature (T c ) with hydrostatic pressure up to 21 kbar are reported for (Lu 1−x Sc x ) 5 Ir 4 Si 10 (0 ≤ x ≤ 1.0). A nonlinear increase in T c with increasing Sc substitution is observed while the room-temperature lattice parameters and unit-cell volume follow the Vegard's Law. The compounds can be separated into two groups. With low Sc content (x=0.05, 0.1, and 0.2) the T c 's are lower and enhanced by external pressure. With high Sc content (x = 0.3, 0.5, 0.95, and 1.0) the T c 's are higher and depressed by external pressure. It is interpreted that phases below a critical value x = 0.3 exhibit an electronic instability and are very sensitive to external pressure. These results can be understood on the basis that the charge-density waves occur in the superconducting compound Lu 5 Ir 4 Si 10 .