Quantum criticality probed by diverging Grüneisen ratios

Alessia Gasparini - March 02 2009

Collaborators: N.T. Huy, D.E. de Nijs, M. Nale, E. Slooten, Y. K. Huang, J. C. P. Klaasse, A. de Visser

Abstract

Quantum phase transitions in correlated metals and their associated quantum critical points (QCP) offer a unique probe to study the emergence of new collective phases. At the QCP the standard Fermi liquid theory for metals breaks down and new concepts are needed. Here we investigate magnetic quantum phase transitions, i.e. transitions from the magnetically ordered to the paramagnetic state, in exemplary systems like U(Rh,Ru)Ge, UCo(Ge,Si) and Ce(Ru,Fe)2Ge2. We use a thermodynamic quantity, namely the Grüneisen ratio Γ ~ α(T)/c(T), to explore the critical behaviour. We compare our results with model calculations, which predict a diverging Grüneisen ratio in the limit T->0.