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Dynamical structure factors of S=1 bond-alternating Heisenberg chains

Takahumi Suzuki·Sei-ichiro Suga
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Abstract

We calculate the dynamical structural factor of the S=1 bond-alternating Heisenberg chain. In the Haldane phase, the lowest excited states form the lower edge of the multimagnon continuum in $0 \leq q \leq q_c$ and the one-magnon mode in $q_c \leq q \leq π$. As the system approaches the gapless point, $q_c$ shifts towards $q=π$ and the largest integrated intensity of the one-magnon mode is decreased. In the singlet-dimer phase, the one-magnon mode appears in $0 \leq q \leq q_c$. As the bond-alternation becomes strong, $q_c$ shifts towards $q=π$. In the antiferromagnetic-ferromagnetic bond-alternation region with a strong ferromagnetic coupling, the lowest excited states form the lower edge of the multimagnon continuum in $0 \leq q \leq 0.2π$ and $0.8π\leq q \leq π$, and the one-magnon mode appears in $0.2π<q<0.8π$. The largest integrated intensity of the one-magnon mode is 93%, which is slightly smaller than that in the S=1 Haldane-gap system. We further discuss the dynamical structural factor in connection with the inelastic neutron-scattering experiments.

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Takahumi Suzuki, Sei-ichiro Suga. 2003-09-08. Dynamical structure factors of S=1 bond-alternating Heisenberg chains. https://doi.org/10.1103/physrevb.68.134429

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