Interaction between two structural blocks and superconductivity inLa2−xMxCuO4(M=Ba,Sr)

Abstract

The combinative energy between two structural blocks in La 2 - x M x CuO 4 (M=Ba,Sr), with different M concentration, has been calculated with holes in different positions in the CuO 2 planes on the basis of a block model. The relationship between the combinative energy and superconductivity has been investigated. The results indicate that there is an interesting correlation among the combinative energy, the T c value, and the positions of the doped holes, which are originated from the substitution of Ba 2 + or Sr 2 + for La 3 + . Although there are some similarities in correlation between La 2 - x Ba x CuO 4 (0.03<x<0.25) and La 2 - x Sr x CoO 4 (0.075≤x≤0.3), there are also some notable differences which may be originated from different properties of the substituted elements: barium and strontium. The results not only suggest that the interaction between perovskite-type and rocksalt-type blocks plays an essential role in high-T c superconductivity, but also give us some clues of the influence of the position of the holes within the CuO 2 plane.