Correlation in transport coefficients of hole-doped CuRhO2 single crystals

To clarify the origin of the nontrivial thermoelectric properties observed in the delafossite oxide CuRhO2 polycrystals, we performed the systematic transport measurements on the single-crystalline CuRhO2 samples. In the parent compound, we found a pronounced peak structure due to a phonon-drag effect in the temperature dependence of the Seebeck coefficient, which was also confirmed by the size effect experiments. In the Mgsubstituted crystals, in contrast to the results of the polycrystals, both the resistivity and the Seebeck coefficient decreased with increasingMg content y. In particular, the coefficient A for the T-2 term of the resistivity and the T-linear coefficient for the Seebeck coefficient at low temperatures are well described within a simple relationship expected for metals, which is also applicable to the correlated materials with low carrier densities.