Study of Heavy Fermions in Ce - and U-Compounds by Low-Temperature Specific Heat Measurements and Other Techniques

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Technically, we built a cryostat, which can cover a wide range of temperature from 0.02 K to 80 K, and a measuring system for specific heat in magnetic field up to 6 T. In addition, our measurements were extended to various transport properties including resistivity, thermoelectric power, etc.Specific heat was measured for a series of dilute-to-dense Kondo compounds Ce_xLa_<1-x>Cu_6. Overall features of magnetic contribution to the low temperature specific heat are quite similar irrespective of Ce-concentration x in Ce_xLa_<1-x>Cu_6. However, we found a profound difference in the low temperature specific heat under magnetic field between the dense and dilute systems, which can be atributed to the coherence of Kondo scattering.We discovered a new series of compounds CeMIn (M = Pd, Pt, Ni) and measured resistivity, susceptibility and specific heat for all of them. These systems exhibit a wide variety of behavior characteristic of Ce-compounds, including dense Kondo, antiferromagnetism, spin fluctuation and mixed-valent behavior.