Thermopower of Ce1–xLaxCu4Al in applied magnetic fields

• The position of the Tmax in S(T) is almost independent of Ce concentration and applied magnetic field.
• The Sph-drag itself is insensitive to the applied magnetic field.
• Below 20 K the S(T) value depends strongly on the magnetic field.
• A field dependent contribution to low temperature S(T) come from the diffusion term S(T) ≈ Sd(T) = αT.
• For low temperature region the Fermi-liquid regime seems suppressed with regard on lack of constant behavior of S/T(T).

Here we report the continued investigations of thermopower S(T) for Ce1–xLaxCu4Al intermetallic alloys, particularly focusing on the influence of the applied magnetic fields. In comparison to CeCu4Al, the substitution of Ce by La reduces the S(T) values. S(T) of Ce1–xLaxCu4Al compounds exhibit positive values and large maximum at Tmax ≈ 30 K. However, the positive sign of S(T) for Ce1–xLaxCu4Al is consistent to that generally observed in Ce-based systems, which is positive due to the location of a narrow Kondo resonance peak slightly above the Fermi energy level (EF). The large peak may be due to the Kondo effect in the presence of a crystal-field splitting (CEF) of the Ce 4f-electron. The peak position and absolute value above Tmax of S(T) is unaffected by an applied magnetic field. At low temperatures the S(T) value depends strongly on the magnetic field. The S/T(T) shows a strong temperature dependence at low temperature which is consistent with the temperature dependence of heat capacity and electrical resistivity.