ELECTRONIC-STRUCTURE EFFECTS IN THE SUPPRESSION OF SUPERCONDUCTIVITY IN HYDROGENATED ZR2RH

The observed suppression of superconductivity on hydrogenation of the C1G-structured intermetallic compound Zr2Rh is explained qualitatively on the basis of the relationship between the electronic density of st ates at the Fermi level, the electron-phonon coupling constant, and T- c. The density of states at the Fermi level obtained from our local de nsity electronic structure calculations has been compared with that es timated from low-temperature specific heat data. In pure Zr2Rh, a rela tively large superconducting transition temperature (T-c similar to 11 K) arises due to the Fermi level lying at the peak of the density of states, while in case of hydrogenated Zr2Rh the lowering of T-c can be ascribed to the filling of bands and the shifting of the Fermi level either to a valley of the density of states (as in case of Zr2RhH2) or to a broad hump in the density of states (as in case of Zr2RhH4).