Resistivity and thermopower of CaB₆ single crystal

The resistivity p and thermopower S of CaB₆ single crystal have been measured at temperatures from 2 to 1100 K in magnetic fields up to 15 T. Temperature dependence of ρ is expressed as [ρ(T)-ρ(0)]oc exp[-(T/T)^1/2] for T≤90 K and T^1.7 for 90 K≤ T≤1100 K, where p0 = 232 μΩ cm. The magnitude of ρ and S is very large suggesting thin concentration of carriers. The temperature dependence of them suggests the conduction is metallic and electron type. ρ and S can be fitted on the basis of free electron model and obtained the Fermi level is situated near the bottom of an electron band with the Fermi energy of 80 K. The experimental and fitting results show this compound is semi-metallic. No scattering anomalies in temperature dependence of ρ were observed and also no sudden change of the Fermi surface accompanied with magnetic transition in S above 100 K including the region where it might be considered to have ferromagnetic transition.