Carrier doping into (Sr,Ba)₂Cu₃O₄)(Cl,Br)₂ with the Cu₃O₄

A trial of the carrier doping into (Sr,Ba)₂Cu₃O₄ (Cl,Ba)₂ with the Cu₃O₄ plane, which is composed of Cu(1)O₂ and extra Cu(2) sublattices, has been carried out through the partial substitution. We have succeeded in obtaining single-phase samples of Ba₂C_3-xLi_xO₄Cl₂ (0 ≤ x ≤ 1.0). With increasing x, the a-axis tends to decrease and the c-axis almost constant. All samples exhibit semiconductive behavior. The electrical resistivity decreases with increasing x up to 0.5 and tends to increase slightly for x > 0.5 due to disorder in the Cu₃O₄ plane through the substitution of Li⁺ for Cu²⁺. Both of the antiferromagnetic transition temperatures with respect to Cu(1) and Cu(2) decrease with increasing x. However, the antiferromagnetic ordering in the Cu(1)O₂ sublattice still remains even for x = 0.5 Considering that the formal valence of Cu is + 2.2 for x = 0.5, holes doped through the Li-substitution may be localized in the Cu(2) site. We will also discuss the possibility of the appearance of the superconductivity in the present system with the Cu₃O₄ plane.