ISSN:
1089-7550
Quelle:
AIP Digital Archive
Thema:
Physik
Notizen:
In various paramagnetic and nearly ferromagnetic substances, the phenomenon of the susceptibility maximum at low temperatures is usually accompanied by the Curie–Weiss susceptibility at higher temperatures; the concurrence of these two features is universally observed in 4d and 5d metals, Laves-phase compounds, and heavy-fermion compounds. No existing theories, however, have been able to explain this concurrence. According to the Fermi-liquid model,1,2 we can express the susceptibility, as a matrix form, exactly in terms of the spin-antisymmetric part of the quasiparticle interaction function gij=gεε' (ε is the quasiparticle energy), χ(T)∝β Ji Jj (j↓(1/1+2βψ)↓i)[ni (1−ni)]1/2[nj(1−nj)]1/2, (1) where ψij=[ni(1−ni)]1/2 gij[nj(1−nj)]1/2, ni is the Fermi distribution function at state i, and β=1/kT. If gij is given, Eq. (1) can be evaluated numerically. We use the g function, which contains logarithmic terms such as (ε−μ)2 ln||ε−μ|| arising from the Fermi-liquid effect (μ is the chemical potential). We find that the calculated result for χ(T) gives a broad maximum at low temperatures because of the logarithmic terms and, at higher temperatures, it follows precisely the Curie–Weiss law, which directly reflects the general form of (1). In conclusion, both the susceptibility maximum and the Curie–Weiss behavior are found to be inherent in any Fermi liquid.
Materialart:
Digitale Medien
URL:
http://dx.doi.org/10.1063/1.344878
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