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Impurity state in Haldane gap for S=1 Heisenberg antiferromagnetic chain with bond doping

Xiaqun Wang·Steffen Mallwitz
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Abstract

Using a new impurity density matrix renormalization group scheme, we establish a reliable picture of how the low lying energy levels of a $S=1$ Heisenberg antiferromagnetic chain change {\it quantitatively} upon bond doping. A new impurity state gradually occurs in the Haldane gap as $J' < J$, while it appears only if $J'/J>γ_c$ with $1/γ_c=0.708$ as $J'>J$. The system is non-perturbative as $1\leq J'/J\leqγ_c$. This explains the appearance of a new state in the Haldane gap in a recent experiment on Y$_{2-x}$Ca$_x$BaNiO$_5$ [J.F. DiTusa, et al., Phys. Rev. Lett. 73 1857(1994)].

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Xiaqun Wang, Steffen Mallwitz. 1995-08-29. Impurity state in Haldane gap for S=1 Heisenberg antiferromagnetic chain with bond doping. https://doi.org/10.1103/physrevb.53.r492

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