Cerium antiferromagnetism

This prediction is a reasonable one for most cerium pnictides, namely CeP, CeAs, CeSb, and CeBi which, in fact, exhibit localized spin moments with an antiferromagnetic ordering of the 4/ electron remaining on each Ce [268]. CeN, however, is a metallic conductor with the corresponding magnetic properties and it only shows Pauli paramagnetism of the metallic electron gas, such that no local spin moment, characteristic for an unpaired electron, can be detected. This behavior leads to the possibility of an electronic formulation according to with one electron left in the conduction band, but... 

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. 

An interesting subset of the 214 phases are the (R,Ce)2Cu04 materials, where usually R=Nd or Pr. These were initially studied as the only conduction-electron high-T superconductors (in all others, holes are the charge carriers). As usually prepared, insulating antiferromagnetic behavior is retained as cerium is added to the end-point... 

CejRhSij is isostructural with the structure type of ErjRhSij (Chevalier et al., 1984) crystal data as derived from X-ray powder diffraction of arc-melted samples annealed at 800°C, 4 d, were as follows P62c, a = 8.210(5), c = 8.410(5). Cc2RhSi3 is antiferromagnetic below = 6 K paramagnetic susceptibilities (1.5-300 K) correspond to trivalent cerium jaff = 2.40 gg, 6p= — 83 K (Chevalier et al., 1984). 

The negative sloping liquidus line at low pressures, unique among the rare earth metals, is also an obvious anomaly. Not obvious from a P—T diagram is the fact that in cerium, one has an element which is both an antiferromagnet (/ -Ce) and a superconductor at high pressures, see fig. 12b (a-, a - and a"-Ce). Cerium is indeed a fascinating element. 

In the RM CsCl-type compounds, when M is a monovalent metal (Cu, Ag, Au) the compounds order antiferromagnetically, while for divalent M (Mg, Zn, Cd, Hg) the compounds generally order ferromagnetically (cerium is more than likely to be an exception since most cerium compounds order antiferromagnetically). In RRh compounds for R = Gd, Tb and Dy the compounds order ferromagnetically and for R = Ho, Er, and Tm they order antiferromagnetically. This is probably a result of a critical RKKY distance falling between the Dy-Dy and Ho-Ho separations in these compounds. 

Edelstein (1968, 1970) has adopted the Coqblin-Blandin model for cerium but with an emphasis on the effect of spin compensation. This point of view was that the decrease or loss of the magnetic moment in a-Ce and the slightly decreased moments in y- and /3-Ce (based on Lock s data) was due to the antiferromagnetic polarization of conduction electrons around the 4f virtual state. Edelstein supported this idea in part by noting an apparent T dependence of the magnetic susceptibility of mixed phase cerium samples above 13 K (Lock, 1957). This temperature dependence had been suggested by Anderson (1967) for the spin compensation contribution to the susceptibility for Kondo alloys. However, subsequent susceptibility measurements of single phase a-Ce (see... 

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