• Disorder and rare events Disorder and rare events completely change the behavior of magnetic systems close to a quantum critical point, leading to quantum Griffiths phases. • In metallic magnets additional long- ranged RKKY interactions couple the rare regions causing non-Ohmic dissipation. • In electronic Griffiths phases: (disordered heavy fermions far from magnetic ordering) this leads to disorder-induced fractionalization and spin liquid behavior (D. Tanaskovic, V. Dobrosavljevic, and E. Miranda, Phys. Rev. Lett. 2005, in press ). • In magnetic Griffiths phases: RKKY interactions lead to dissipative freezing of magnetic droplets and the formation of cluster-glass phases (V. Dobrosavljevic and E. Miranda, Phys. Rev. Lett. 94, 187203 (2005)). • Both mechanism can lead to disorder- driven non-Fermi liquid behavior . Recent review: E. Miranda and V. Dobrosavljevic, E. Miranda and V. Dobrosavljevic, RKKY Interactions and Dissipation in Metallic Griffiths RKKY Interactions and Dissipation in Metallic Griffiths Phases Phases Vladimir Dobrosavljevic, Florida State University, DMR-0234215 Vladimir Dobrosavljevic, Florida State University, DMR-0234215 1 2 3 4 RKKY RKKY Griffiths droplets RKKY interactions mediating non-Ohmic dissipation in magnetic Griffiths phases (top). Phase diagram of the induced cluster- glass