J M Lawrence et al 1981 Rep. Prog. Phys. 44 1 doi:10.1088/0034-4885/44/1/001
J M Lawrence, P S Riseborough and R D Parks
Show affiliationsValence fluctuation phenomena occur in rare-earth compounds in which the proximity of the 4f level to the Fermi energy leads to instabilities of the charge configuration (valence) and/or of the magnetic moment. The authors review the experimental results observed in the subset of such systems for which the 4f ions form a lattice with identical valence on each site. The discussion includes key thermodynamic experiments, such as susceptibility and lattice constant, and spectroscopic experiments such as XPS and neutron scattering. This is followed by a review of existing theoretical work concerning both the ground states and the isomorphic phase transitions which occur in such compounds; the emphasis is on those aspects which make valence fluctuation phenomena such a challenging many-body problem.
75.30.Mb Valence fluctuation, Kondo lattice, and heavy-fermion phenomena
75.40.-s Critical-point effects, specific heats, short-range order
65.40.-b Thermal properties of crystalline solids
79.60.Bm Clean metal, semiconductor, and insulator surfaces
75.30.Cr Saturation moments and magnetic susceptibilities
75.30.Kz Magnetic phase boundaries (including magnetic transitions, metamagnetism, etc.)
Condensed matter: electrical, magnetic and optical
Issue 1 (January 1981)
J M Lawrence et al 1981 Rep. Prog. Phys. 44 1
W W Heidbrink et al 2004 Plasma Phys. Control. Fusion 46 1855
María Jesús Pareja and Malcolm A H MacCallum 2006 Class. Quantum Grav. 23 5039
Yuri M Pis'mak et al 2009 J. Phys. A: Math. Theor. 42 095003
Franz Wegner 2007 J. Phys.: Condens. Matter 19 406218
Dan Zhang et al 2010 J. Neural Eng. 7 016010