The enhancement of the superconducting transition temperature of ${\mathrm{Lu}}_5$${\mathrm{Ir}}_4$${\mathrm{Si}}_{10}$ from 3.8 to 9.1 K under pressure is caused by the suppression of an electronic phase transition which results in the partial gapping of the Fermi surface. Using electrical resistivity at ambient and high pressure, bulk-modulus, heat-capacity, upper-critical-magnetic-field, and static-magnetic-susceptibility measurements, we estimate that the density of electronic states at the Fermi level is reduced by 36% due to this phase transition. The transition, which occurs at 79 K at ambient pressure, has the experimental characteristics indicative of charge- or spin-density-wave formation.

• Received 31 March 1986

DOI:https://doi.org/10.1103/PhysRevB.34.4590