Valence heavy fermion

The discovery of new physical effects in intermetallic compounds, such as intennediate valence, heavy fermions and Kondo systems, coexistence of magnetism and superconductivity, etc., has stimulated much interest in these materials. It is also necessary to mention the powerful permanent magnets based on rare-earth intermetallides. A complex approach to the investigation of the composition, crystal structure and properties of these intermetallic compounds has been outlined and gives the possibility of solving the important problem of the determination of correlations between these characteristics. 

Wachter, P. Intermediate valence and heavy fermions, in Gschneidner Jr., K.A., Eyring, L., editors. Handbook on the Physics and Chemistry of Rare Earths. Amsterdam North-Holland Publishing Company 1994, chap. 132. 

M. Loewenhaupt and K.H. Fischer, Valence-fluctuation and heavy-fermion 4f systems 1... 

The compounds that do not order magnetically are represented by a triangle (7 ) on a logarithmic scale because of their wide range of values (from a few degrees for the heavy-fermion compounds to a thousand for the intermediate-valence compounds). The Greek letters a, P and y in fig. 1 represent the respective allotropic phases of Ce metal for comparison. 

IV) Within this region are included all the Ce-X compounds that do not order magnetically - heavy-fermion compounds and intermediate-valence compounds. 

Boucherle, J.X., F. Givord, F. Lapierre, P Lejay, J. Peyrard, J. Odin, J. Schweizer and A. Stunault, 1987b, in Theoretical and Experimental Aspects of Valence Fluctuations and Heavy Fermions, eds L.C. Gupta and S.K. Malik (Plenum, New York) p. 485. 

Steglich, F., 1985, in Theory of Heavy Fermions and Valence Fluctuations, Springer Series in Solid State Sciences, Vol. 62, eds T. Kasuya and T. Sato (Springer, Berlin). 

In chapter 98, Julian Sereni adds significantly to an evaluation of systematic, experimental low-temperature studies of the ambivalent behaviors of cerium (ferromagnetism, antiferromagnetism, spin glass, superconductivity, valence fluctuations, heavy Fermion, Kondo and spin fluctuations) which depend upon its environment in materials. The systematic conclusions arrived at should provide new data against which the theory can be advanced. 

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