Quasiparticles in heavy-fermion systems
- Max-Planck-Institut fuer Physik komplexer Systeme, Stuttgart (Germany)
The authors discuss different physical origins of heavy-fermion behavior and the corresponding theoretical models. One possible origin is the Kondo effect. In Kondo-lattice systems a low energy scale k{sub B}T results from singlet-triplet excitations. The Fermi surface at low T can be reliably calculated within renormalized band theory. Above the coherence temperature the systems can be described by a collection of independent Kondo impurities. Superconductivity results when the heavy quasiparticles form Cooper pairs. In Nd{sub 2{minus}x}Ce{sub x}CuO{sub 4} and related systems the observed heavy-fermion behavior is unrelated to the Kondo effect. Instead, strong antiferromagnetic correlations of the conduction electrons which couple weakly to the 4f ions are here responsible for the appearance of a low-energy scale. When the systems becomes superconducting the heavy quasiparticles do not participate in the formation of Cooper pairs and the corresponding low energy excitations remain unaffected.
- Sponsoring Organization:
- USDOE
- OSTI ID:
- 102546
- Report Number(s):
- CONF-9309321-; ISSN 0022-2291; TRN: 95:019703
- Journal Information:
- Journal of Low Temperature Physics, Vol. 95, Issue 1-2; Conference: International workshop on cuprate and heavy fermion superconductors, Cologne (Germany), 27-30 Sep 1993; Other Information: PBD: Apr 1994
- Country of Publication:
- United States
- Language:
- English
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