Fermi Surface Properties, Metamagnetic Transition and Quantum Phase Transition of CeRu2Si2 and Its Alloys Probed by the dHvA Effect

This article describes the Fermi surface properties of CeRu2Si2 and its alloy systems CeRu2(SixGe1−x)2 and CexLa1−xRu2Si2 studied by the de Haas–van Alphen (dHvA) effect. We pay particular attention to how the Fermi surface properties and the f electron state change with magnetic properties, in particular how they change associated with metamagnetic transition and quantum phase transition. After summarizing the important physical properties of CeRu2Si2, we present the magnetic phase diagrams of CeRu2(SixGe1−x)2 and CexLa1−xRu2Si2 as a function of temperature, magnetic field and concentration x. From the characteristic features of the magnetic phase diagram, we argue that the ferromagnetic interaction in addition to the antiferromagnetic interaction and the Kondo effect is responsible for the magnetic properties and that the metamagnetic transitions in these systems are relevant to the ferromagnetic interaction. We summarize the Fermi surface properties of CeRu2Si2 in fields below the metamagnetic transiti...