  Defects in frustrated antiferromagnetic spin chains are universally present
in geometrically frustrated systems. We consider the defects of the
one-dimensional, spin-$s$ XXZ chain with single-ion anisotropy on a periodic
chain with $N$ sites that was famously studied by Haldane. For $N$ odd the
antiferromagnetic model is frustrated, and the ground state must include a
soliton defect. We consider the Heisenberg interaction perturbatively and
determine the corresponding perturbative solitonic ground state. Then we
compute the entanglement spectrum, entanglement entropy (EE), capacity of
entanglement (CE), and spin correlations in the solitonic ground state. For
weak frustration, we find an algebraic violation of the area law for the EE
consistent with recent results on weakly frustrated chains. Our analysis then
moves beyond the weak frustration regime, and we obtain a novel extensive
scaling law for the EE when strong frustration prevails, signalling large
entanglement, and failure of the quasiparticle interpretation in this regime.
Enhanced frustration results in less total correlations, but relatively more
nonlocal correlations.
