Inelastic neutron scattering study on the AFM uniform spin-1/2 chain compound CuSb2O6

TL;DR

This study used inelastic neutron scattering to investigate magnetic excitations in CuSb2O6, revealing a small anisotropy-induced energy gap in the AFM spin-1/2 chain compound.

Contribution

It provides detailed experimental evidence of the anisotropy-induced gap in the magnetic excitation spectrum of CuSb2O6, aligning with theoretical predictions.

Findings

Magnetic excitations appear between 1.8 and 13 meV below TN.

A 1.8 meV gap is observed due to spin anisotropy.

Excitations are gapless above TN, confirming the gap's magnetic origin.

Abstract

We carried out inelastic neutron scattering experiments on a powdered sample of the antiferromagnetic (AFM) uniform spin-1/2 chain compound CuSb2O6.The magnetic excitations appear in the energy range of 1.8 to 13 meV at 2.5 K below the AFM transition temperature (TN = 8.7 K).The gap value (1.8 meV) is close to that evaluated from the specific heat (1.51 meV). The excitations at 12.5 K (> TN) appear gapless. Thus, the 1.8 meV gap is caused by some anisotropy in spin-wave excitations. The gap excitations are strongest at 0.48 corresponding to a length of 0.66 nm. This result is consistent with the theoretical one that the interaction in a Cu pair with a length of 0.65562 nm (Jab) is strongest. The magnetic excitations can be explained by the AFM uniform XXZ chain with Jab = 6.437 meV and DJab = 0.063 meV. The 1.8 meV gap is caused by the small Ising anisotropy (DJab/Jab = 0.0098).