Fermi surface studies of the skutterudite superconductors LaPt4Ge12 and PrPt4Ge12

Abstract

We report on comprehensive de Haas--van Alphen (dHvA) and electronic band-structure studies of the superconducting skutterudites ${\mathrm{LaPt}}_{4}{\mathrm{Ge}}_{12}$ (${T}_{c}=8.3$ K) and ${\mathrm{PrPt}}_{4}{\mathrm{Ge}}_{12}$ (${T}_{c}=7.9$ K). Both materials show very rich spectra of dHvA oscillations with similar and only slightly varying angular-dependent frequencies. The spectral richness can partly be rationalized by the elaborated electronic band structures resulting in several Fermi surfaces built by six different bands. The effective cyclotron masses of both superconductors lie between about 0.5 and 1.1 times the free-electron mass. Although these values are small, we find moderate mass enhancements between about 2 and 4 when comparing to the calculated masses. Our results evidence the localized character of the $4f$ electrons in the Pr compound and are in line with an electron-phonon mediated multiband superconductivity, largely identical for both compounds.