Study on the in-plane electrical resistivity and thermoelectric power in single crystals of La 2-x Ba x CuO 4

The in-plane electrical resistivity and thermoelectric power have been measured on single crystals of La2-xBaxCuO4 at around x=0.125.The room temperature resistivity and thermopower have their maximum values at x=0.125,indicating that the carrier concentration is the minimum and the carriers are most strongly localized at x=0.125.The observed semiconductor-like behaviour can be well described by the weak-localized quasi-two-dimensional state.The steep rise in electric resistivity of the sample at x=0.125 below 70K is attributed to the formation of static stripe-order of holes and spins,which are pinned by the low-temperature tetragonal (LTT) structure,as discovered in La1.48Nd0.4Sr0.12CuO4.The temperature dependence of electric resistivity below 70K is still well described by the formula ρ ∝ lnT.A definite change in the slope of thermopower is observed at the low-temperature orthorhombic-LTT structural phase transition temperature.The origin of the 1/8 anomaly is discussed in the text.