Novel Quantum Criticality in CeRu$_2$Si$_2$ near Absolute Zero Observed   by Thermal Expansion and Magnetostriction
  We report linear thermal expansion and magnetostriction measurements for CeRu$_2$Si$_2$ in magnetic fields up to 52.6 mT and at temperatures down to 1 mK. At high temperatures, this compound showed Landau-Fermi-liquid behavior: The linear thermal expansion coefficient and the magnetostriction coefficient were proportional to the temperature and magnetic field, respectively. In contrast, a pronounced non-Fermi-liquid effect was found below 50 mK. The negative contribution of thermal expansion and magnetostriction suggests the existence of an additional quantum critical point. 
J. Yoshida, S. Abe, D. Takahashi, Y. Segawa, Y. Komai, H. Tsujii, K.   Matsumoto, H. Suzuki, and Y. \=Onuki