Intermetallic Fermi surfaces

Y. Onuki and A. Hasegawa, Fermi surfaces of intermetallic compounds 1... 

These cases can be contrasted by most uranium intermetallics, which have Fermi surfaces in good agreement with LDA calculations which treat the f electrons as band states (IQ. In the one case where a mixed valent Fermi surface is known (CeSno), it is also in excellent agreement with an LDA f band calculation (T8-19L with a mass renormalization of five due to a self-energy correction resulting from virtual spin fluctuation excitations (2Q). Notice the different dynamic correlations used to explain the mass renormalizations in the f core and f band cases. 

The study of Coulomb transitions is especially valuable in actinide metals and intermetallic compounds (McEwen et al. 1990, Osborn et al. 1990). Because of the greater radial extent of the 5f charge distribution, the actinide f electrons tend to hybridise more strongly with band electron states than their lanthanide counterparts. In a number of actinide metals, it is evident that the f electrons contribute to the cohesive energy through the formation of 5f bands, either by direct f-f overlap, as in a-uranium, or by hybridisation with conduction bands, as in URUj or URhj (Oguchi and Freeman 1986, Johansson et al. 1987). In these cases, relativistic band theory is successful in predicting lattice constants, photoemission and Fermi surfaces (Arko et al. 1985) provided the f states are included as itinerant. 

De Haas-van Alphen (dHvA)-type quantum oscillations as observed in the sound velocity and sound attenuation provide important information about the Fermi surface and the electron-phonon interaction (Roberts 1968, Fawcett et al. 1980). This technique has been successfully applied to intermetallic rare-earth compounds as discussed below. Recent progress in dHvA techniques for heavy-fermion materials (Taillefer et al. 1987, Reinders et al. 1986) should make similar MAQO experiments also possible. Compounds studied so far are LaAg, LaB5, LaAlj, RBj, CeSn3, CeB, CeCu and CePbj. 

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