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arXiv · 1912.01576

Magnetic field induced bound states in spin-$\frac{1}{2}$ ladders

Mithilesh Nayak·Dominic Blosser·Andrey Zheludev·Frédéric Mila
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Abstract

Motivated by the intriguing mode splittings in a magnetic field recently observed with inelastic neutron scattering in the spin ladder compound (C$_5$H$_{12}$N)$_2$CuBr$_4$ (BPCB), we investigate the nature of the spin ladder excitations using DMRG and analytical arguments. Starting from the fully frustrated ladder, for which we derive the low-energy spectrum, we show that bound states are generically present close to $k=0$ in the dynamical structure factor of spin ladders above $H_{c 1}$, and that they are characterized by a field-independent binding energy and an intensity that grows with $H-H_{c 1}$. These predictions are shown to explain quantitatively the split modes observed in BPCB.

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Mithilesh Nayak, Dominic Blosser, Andrey Zheludev, Frédéric Mila. 2020-02-26. Magnetic field induced bound states in spin-$\frac{1}{2}$ ladders. https://doi.org/10.1103/physrevlett.124.087203

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