From chessboard of bipolarons of size 4a in cubic La7/8Sr1/8MnO3 to stripes of the same bipolarons in layered high Tc cuprates

TL;DR

This paper proposes a bipolaron-based model for high-temperature superconductivity in cuprates, linking charge order, stripe formation, and superconducting transition temperature through bipolarons of size 4a.

Contribution

It introduces a novel bipolaronic framework explaining stripe patterns and charge/spin density waves in high Tc cuprates, connecting structural and magnetic pairings to superconductivity.

Findings

Bipolarons of size 4a form in La7/8Sr1/8MnO3 and cuprates.

Stripe patterns of bipolarons and spins are explained by the model.

The model reproduces observed charge and spin density wave laws.

Abstract

The compound La1-xSrxMnO3 exhibits a charge order (CO) state at $x\approx 1/8$ and $T<T_{co}$, which recalls the CO state with a decrease in the temperature of the superconducting transition, $T_c$, observed in all cuprates at this doping value. 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 $4a$ resulting from structural and antiferromagnetic pairings of hole-rich orbital polarons of size $2a$. They are intertwined with hole-poor domains in a disordered state at $T>T_{co}$ which become ordered on a chessboard organized in a 3D-order state of ferromagnetically paired polarons at $T<T_{co}$. Applied to the CuO$_2$ 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 $\delta=1/8$, a charge density wave with $q=1/4$, the Yamada laws $\delta(x)=x$ and $T_c\propto \delta$ and a decrease of $T_c$ at x=1/8. This work invokes relevance of a bipolaronic origin of high $T_c$ superconductivity, in which bipolarons of size $4a$ can play a major role.