Local excitations of lattice and magnetic origins measured in the two-dimensional metallic state of La7/8Sr1/8MnO3 reveal the existence of bipolarons of size 4a
Martine Hennion, Alexandre Ivanov, Claudine Lacroix and Bernard Hennion
The compound La1−xSrxMnO3 exhibits a charge order (CO) state at x ≈ 1/8 and T Tco which become ordered on a chessboard organized in a 3D-order state of ferromagnetically paired polarons at T <Tco. Applied to the CuO2 planes of the cuprates of the “214” family, this model produces stripes of bipolarons intertwined with stripes of antiferromagnetically arranged spins, hole-poor, both of size 4a, leading to a spin density wave with a wave vector δ = 1/8, a charge density wave with q = 1/4, the Yamada laws δ(x) = x and Tc ∝ δ and a decrease of Tc at x=1/8. This work invokes relevance of a bipolaronic origin of high Tc superconductivity, in which bipolarons of size 4a can play a major role.