MAGNETIC-PROPERTIES OF STRONGLY DISORDERED ELECTRONIC SYSTEMS

We present a unified global perspective on the magnetic properties of strongly disordered electronic systems, with special emphasis on the c ase where the ground state is metallic. We review the arguments for th e instability of the disordered Fermi liquid state towards the formati on of local magnetic moments, and argue that their singular low temper ature thermodynamics are the 'quantum Griffiths' precursors of the qua ntum phase transition to a metallic spin glass; the local moment forma tion is therefore not directly related to the metal-insulator transiti on. We also review the mean-field theory of the disordered Fermi liqui d to metallic spin glass transition and describe the separate regime o f 'non-Fermi liquid' behaviour at higher temperatures near the quantum critical point. The relationship to experimental results on doped sem iconductors and heavy-fermion compounds is noted.