Edge singularities in high-energy spectra of gapped one-dimensional magnets in strong magnetic fields

Abstract

We use the dynamical density matrix renormalization group technique to show that the high-energy part of the spectrum of a S=1 Haldane chain, placed in a strong external magnetic field $H$ exceeding the Haldane gap $\Delta$, contains edge singularities, similar to those known to exist in the low-energy spectral response. It is demonstrated that in the frequency range $\omega \gtrsim \Delta$ the longitudinal (with respect to the applied field) dynamical structure factor is dominated by the power-law singularity $S^{\parallel }(q=\pi ,\omega )\propto (\omega -{\omega }_0{)}^{-{\alpha }^{\prime }}$. We study the behavior of the high-energy edge exponent ${\alpha }^{\prime }$ and the edge ${\omega }_0$ as functions of the magnetic field. The existence of edge singularities at high energies is directly related to the Tomonaga-Luttinger liquid character of the ground state at $H>\Delta$ and is expected to be a general feature of one-dimensional gapped spin systems in high magnetic fields.

(v2) error in Eq.(11) corrected

Cited by in corpus (3)

• Phenomenology of One-Dimensional Quantum Liquids Beyond the Low-Energy Limit
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