Spin texture in weakly doped $Cu{0}_2$ planes explaining magnetic correlation length and Raman scattering experiments

Abstract

A model of $Cu{O}_2$ planes weakly doped with partially delocalised holes is considered. The effect of such a hole on the background AFM spin texture can be represented by a purely magnetic Hamiltonian $H=-{\sum }_{(ijk)}({\vec{S}}_i\cdot {\vec{S}}_j\times {\vec{S}}_k{)}^2$, where the summation is over the four triangles of a single plaquette. We show that this model of randomly distributed chiral spin defects leads to an in--plane spin correlation length approximately described by ${\xi }^{-1}(x,T)={\xi }^{-1}(0,T)+{\xi }^{-1}(x,0)$, consistent with neutron scattering experiments on $L{a}_{2-x}S{r}_{x}Cu{O}_4$. Further, this model leads to favourable comparisons with $B_{1g}$ Raman scattering results for the same cuprate system.

14 pages, 1 figure available on request from [email protected]