Recent progress in the study of heavy-fermion systems

Recent experiments on heavy-fermion systems have focused on the following issues: (i) non-Fermi-liquid behavior occurring either because of cooperative effects at a magnetic instability, i.e. at a T=0 phase transition between magnetically ordered and nonmagnetic groundstates driven by parameters such as chemical composition or pressure, or because of single-ion effects such as the two-channel Kondo effect or a distribution of Kondo temperatures; (ii) the symmetry of the order parameter in heavy-fermion superconductors and the interplay of (often weak) magnetism and superconductivity. A review of recent developments in these areas is given