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出典:『Wikipedia』 (2011/04/19 19:12 UTC 版)

英語による解説

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In solid-state physics, heavy fermion materials are a specific type of intermetallic compounds, containing elements with 4f or 5f electrons. They have a low-temperature specific heat whose linear term is up to 1000 times larger than the value expected from the free-electron theory. The properties of the heavy fermion compounds derive from the partly filled f-orbitals of rare earth or actinide ions which behave like localized magnetic moments. The name "heavy fermion" comes from the fact that below a characteristic temperature (typically below 10K) the conduction electrons in these metallic compounds behave as if they had an effective mass up to 1000 times the free-electron mass. This large effective mass is also reflected a large contribution to the resistivity from electron-electron scattering via the Kadowaki Woods ratio. The heavy fermion behavior has been found in a broad variety of states including metallic, superconducting, insulating and magnetic states. Characteristic examples are CeCu₆, CeAl₃, CeCu₂Si₂, YbAl₃, UBe₁₃ and UPt₃.