T-Linear Resistivity and Thermoelectric Power in Heavy-Fermion Spinel LiV2O4

Through the comprehensive analysis of the electrical resistivity and the thermoelectric power in the heavy-fermion spinel LiV2O4 which exhibits the coherent (T ≤ T*)–incoherent metallic phase (T > T*) crossover at T* ≈ 20 K, we have shown that the resistivity is approximately linear for temperatures between 5 K and T* in the coherent phase similar to the behavior above 2T* in the incoherent phase and these T-linear behaviors are reproduced in terms of the Planckian dissipation bound successfully used in previous analyses in high-temperature superconductors and heavy-fermion metals. The thermoelectric power analysis based on the Mott formula in the coherent phase suggests that the relaxation time for the resistivity is independent of the density of states [D(EF)] of electrons at the Fermi level EF. This peculiar property of relaxation is one of the major features of the Planckian bound that is not found in usual microscopic dissipations due to electron–electron, electron–phonon, and electron–impurity scatterings, and contrasts highly with the D(EF)3 dependence on the relaxation rate in the Kadowaki–Woods relation at temperatures below 2 K. Thus, the application of the Planckian bound to the transport properties in the coherent phase is strongly supported.