ac susceptibility and static magnetization measurements of CeRu2Si2 at small magnetic fields and ultralow temperatures

Abstract

The magnetic properties of CeRu2Si2 at microkelvin temperatures (down to 170 μK) and ultrasmall magnetic fields (0.02∼6.21 mT) are investigated experimentally. The simultaneously measured ac susceptibility and static magnetization show neither evidence of the magnetic ordering, superconductivity down to the lowest temperatures nor conventional Landau Fermi-Liquid behavior. The results imply the magnetic transition temperature in undoped CeRu2Si2 is very close to absolute 0 K. The possibility for proximity of CeRu2Si2 to the quantum critical point without any doping is discussed.