Gap excitations in a four-leg Heisenberg spin tube antiferromagnet

TL;DR

This study uses inelastic neutron scattering to reveal that magnetic excitations in a four-leg Heisenberg spin tube antiferromagnet are dominated by next-nearest-neighbor interactions, challenging previous models and showing partial frustration effects.

Contribution

It identifies the dominant next-nearest-neighbor interactions in a four-leg spin tube system, revising prior bond-alternation models and highlighting geometric frustration effects.

Findings

Next-nearest-neighbor antiferromagnetic couplings dominate

The system behaves as an almost perfect one-dimensional spin tube

Partial geometric frustration causes incommensurate spin correlations

Abstract

Inelastic neutron scattering is used to investigate magnetic excitations in the quasi-one-dimensional quantum spin-liquid system Cu2Cl4 D8C4SO2. Contrary to previously conjectured models that relied on bond-alternating nearest neighbor interactions in the spin chains, the dominant interactions are actually next-nearest-neighbor in-chain antiferromagnetic couplings. The appropriate Heisenberg Hamiltonian is equivalent to that of a S = 1/2 4-leg spin-tube with almost perfect one dimensionality and no bond alternation. A partial geometric frustration of rung interactions induces a small incommensurability of short-range spin correlations.