Spin-Vacancy-Induced Long-Range Order in a New Haldane-Gap Antiferromagnet

TL;DR

This study investigates a new quasi-one-dimensional antiferromagnet, revealing how doping induces long-range magnetic order in a Haldane-gap system, challenging previous understanding of its magnetic ground state.

Contribution

It reports the first observation of doping-induced long-range order in a Haldane-gap antiferromagnet, using multiple experimental techniques to analyze magnetic properties.

Findings

Inter-chain interactions nearly destroy the Haldane gap

Doping with nonmagnetic ions induces magnetic order

Magnetic excitation spectrum remains gapped without doping

Abstract

Magnetic susceptibility, high-field magnetization and inelastic neutron scattering experiments are used to study the magnetic properties of a new S=1 quasi-1-dimensional antiferromagnet PbNi2V2O8. Inter-chain interactions are shown to be almost, but not quite, strong enough to destroy the nonmagnetic singlet ground state and the energy gap in the magnetic excitation spectrum. Substituting nonmagnetic Mg$^{2+}$ (S=0) ions for Ni$^{2+}$ (S=1) induces a magnetically ordered state at low temperatures. To our knowledge this is the first observation of doping-induced long-range order in a Haldane-gap system.