Angle-resolved measurements of the de Haas-van Alphen (dHvA) effect are reported in LaRu2Ge 2 which is a reference material for the ferromagnetic CeRuzGe 2. At least five dHvA branches have been observed. These results closely resemble those in CeRu2Ge2. The measured effective masses are in the range of 0.4-2.0rn o.
1. Introduction
Intermetallic rare earth compounds having the ThCr2Si 2 structure show a wide variety of unusual magnetic and electrical properties such as heavy fermion, superconductivity, Kondo lattice, paramagnetism, antiferromagnetism, ferromagnetism and spin wave magnetic structures. Though those compounds are ternary, they have a simple crystal structure and some of those compounds can be prepared as single crystals with very high purity to be performed the de Haasvan Alphen (dHvA) effect measurement. Thus those compounds are suitable for investigation for various many-body aspects of the properties of electrons in metals.
CeRu2Si 2 [1] is a typical nonmagnetic heavy fermion compound which has large electronic specific heat coefficient T, 385m J/K2 mol, suggesting the strong renormalization of fermion mass. In fact, the heavy carriers with the cyclotron mass of 20m 0 are detected in the dHvA experiment [2]. Recently the magnetoresistance and dHvA effect in CeRu2Si 2 and LaRu2Si 2 were measured by 0nuki et al. [3]. These results imply that the 4f electrons in CeRu2Si 2 are itinerant and the Fermi surfaces of CeRu2Si 2 has different topology from that of LaRu2Si 2.
CeRu2Ge 2 has been previously described to be ferromagnetic below 8 K [4,5], which is compared to the archetype heavy-fermion system CeRu2Si 2. The recent inelastic neutron-scattering experiments [6] show a Korringa-type linear T dependence of the magnetic relaxation rate between 200 and 8 K, which is expec-