IPA-CuCl$_3$: a S=1/2 Ladder with Ferromagnetic Rungs

TL;DR

This paper reveals that IPA-CuCl3 is better described as a weakly coupled spin ladder with ferromagnetic rungs, making it an ideal candidate for studying Haldane-gap phenomena with neutron scattering.

Contribution

The study provides a new structural and magnetic model for IPA-CuCl3, showing it consists of antiferromagnetic-leg ladders with ferromagnetic rungs, contrasting previous chain-based descriptions.

Findings

Revealed the ladder structure with antiferromagnetic legs and ferromagnetic rungs.

Identified the system as a Haldane S=1 antiferromagnet.

Measured a gap energy of 1.17 meV and zone-boundary energy of 4.1 meV.

Abstract

The spin gap material IPA-CuCl3 has been extensively studied as a ferromagnetic-antiferromagnetic bondalternating S = 1/2 chain. This description of the system was derived from structural considerations and bulk measurements. New inelastic neutron scattering experiments reveal a totally different picture: IPA-CuCl3 consists of weakly coupled spin ladders with antiferromagnetic legs and ferromagnetic rungs. The ladders run perpendicular to the originally supposed bondalternating chain direction. The ferromagnetic rungs make this system equivalent to a Haldane S = 1 antiferromagnet. With a gap energy of 1.17(1) meV, a zone-boundary energy of 4.1(1) meV, and almost no magnetic anisotropy, IPA-CuCl3 may the best Haldane-gap material yet, in terms of suitability for neutron scattering studies in high magnetic fields.