Hall coefficient of the oxygen-intercalated La214 superconductor in the low hole concentration region

Abstract

The temperature dependence of the Hall coefficient ( R H) of La 2CuO 4+ δ was studied in the low oxygen concentration range δ=0.015–0.030 where the phase separation into the antiferromagnetic and the superconducting states has been observed. The Hall number derived from the R H at room temperature agreed with the hole concentration of 0.03–0.06/Cu in the system, which is similar to the La 2− x Sr x CuO 4. However, in the lowest hole concentration region, the R H increased rapidly below around 250 K with lowering the temperature to 90 K where the R H started to decrease on further cooling. The drop in the R H below 90 K indicates a development of the one-dimensional charge transport in the system. The results are quite different from those observed in the similarly low-doped La 2− x Sr x CuO 4 system and discussed in terms of the phase separation, staging and charged-stripe formation.