Anomalous Behaviors in Transport Properties of CeCu_6 and CeCu_<5.9>Au_<0.1>(Condensed matter: electronic structure and electrical, magnetic, and optical properties)

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We have investigated the thermoelectric power (TEP) and Hall coefficient (R_H), along with the field dependence of Hall resistivity (ρ_H) and magnetoresistance (MR) in single crystals of CeCu_<5.9>Au_<0.1> and CeCu_6. In both compounds, R_H is highly anisotropic with respect to the field direction below 〜10K. For H‖[001], a negative minimum in ρ_H and a positive MR peak grow at low temperatures near 1.7T, where a metamagnetic-like anomaly was reported for CeCu_6. The Au substitution induces drastic changes in R_H depending on the magnetic field direction, which is discussed in correlation with the predicted change in the Fermi surface across the quantum critical point. In CeCu_<5.9>Au_<0.1>, an unexpectedly large positive MR has been found at low temperatures and in low fields; its origin is discussed in comparison with the Hall resistivity. For all the principal axes, the Au-substitution effect on TEP is minor in both magnitude and anisotropy down to 〜1.5K, suggesting no essential change in the electronic structure in the energy region above a few K.
社団法人日本物理学会の論文
2007-05-15