Fermi surface inLaRhSi3andCeRhSi3

Abstract

We report on de Haas-van Alphen (dHvA) effect measurements at ambient pressure and band-structure calculations for ${\text{LaRhSi}}_{3}$ and ${\text{CeRhSi}}_{3}$, whose crystal structures lack space-inversion symmetry. For ${\text{LaRhSi}}_{3}$, dHvA frequencies up to $\ensuremath{\sim}11\text{ }\text{kT}$ with effective masses up to $\ensuremath{\sim}1.6{m}_{e}$, where ${m}_{e}$ is the free-electron mass, are observed. The observed and the calculated Fermi surfaces are in satisfactory quantitative agreement. The energy splitting of bands due to the spin-orbit coupling is estimated to be of the order of ${10}^{2}\text{ }\text{K}$. For ${\text{CeRhSi}}_{3}$, dHvA frequencies up to $\ensuremath{\sim}12\text{ }\text{kT}$ with effective masses up to $\ensuremath{\sim}19{m}_{e}$ are observed. The dHvA frequency branches are definitely different from those observed in ${\text{LaRhSi}}_{3}$ and are difficult to explain with the ${\text{LaRhSi}}_{3}$ Fermi surface. This leads to the conclusion that the $\text{Ce}\text{ }4f$ electrons in ${\text{CeRhSi}}_{3}$ are itinerant in the antiferromagnetic state at ambient pressure. The Fermi surface resulting from a band-structure calculation in which the $\text{Ce}\text{ }4f$ electrons are treated as itinerant can provide a plausible explanation for the observed frequency branches, although the quantitative agreement is rather limited. The comparison of the calculated density of states with the Sommerfeld coefficient gives the mass enhancement factor of 8.