Fermi Surface of ThRu2Si2 as a Reference to the Strongly Correlated Isostructural Metals Investigated by Quantum Oscillations

We have successfully grown a high-quality single crystal of ThRu2Si2 with the residual resistivity ratio (RRR) of 120, which is a reference compound to the heavy-fermion systems CeRu2Si2 and URu2Si2 crystallizing in the tetragonal ThCr2Si2-type structure, and observed the quantum oscillations (de Haas–van Alphen effect). The result is compared with the Fermi surfaces of CeRu2Si2 and URu2Si2 as well as the band structure calculations. The main features of Fermi surface topology of ThRu2Si2 are similar to those of the heavy-fermion compound CeRu2Si2, indicating that the 4f electron in CeRu2Si2 contributes to the conduction band. On the other hand, the Fermi surfaces of ThRu2Si2 significantly differ from those obtained for URu2Si2, suggesting the itinerant nature of 5f electrons rather than the conventionally assumed localized 5f2 configuration.