Unified description of resistivity and thermopower of Pr2Ir2O7: Possible influence of crystal field excitation in a Kondo lattice

We present experimental evidence of incoherent Kondo scattering as the source of resistivity minima in bulk polycrystalline and nanocrystalline Pr2Ir2O7. The temperature dependence of thermopower shows a positive maximum at high temperature followed by a negative minimum at low temperature, with the sign inversion occurring at a much higher temperature than T-K. Moreover, we observe little correlation between T-K and intersite coupling strength given by vertical bar theta(CW)vertical bar. We describe the temperature dependence of thermopower and resistivity within the framework of crystal field excitation in a Kondo lattice.