Universal charge transport of the Mn oxides in the high temperature limit

摘要

We have found that various Mn oxides have the universal resistivity andthermopower in the high temperature limit. The resistivities and thermopowersof all the samples go toward constant values of 7$\pm$1 m$\Omega$cm and$-79\pm$3 $\mu$V/K, which are independent of carrier density and crystalstructures. We propose that the electric conduction occurs in a highlylocalized way in the high temperature limit, where the exchange of entropy andcharge occurs in the neighboring Mn$^{3+}$ and Mn$^{4+}$ ions.