A Neutron Scattering Study of Magnetic Excitations in the Spin Ladder (VO)2P2O7

TL;DR

This study uses inelastic neutron scattering to identify and analyze magnetic excitations in (VO)2P2O7, revealing three modes that support the spin-ladder model and uncover a previously unreported excitation.

Contribution

First experimental observation of multiple magnetic excitations in (VO)2P2O7 supporting the spin-ladder model, including a novel mode not predicted by existing theories.

Findings

Evidence for three magnetic excitations at 3.5, 6.0, and 14 meV.

The 3.5 meV mode aligns with the one-magnon gap predicted by the spin-ladder model.

Discovery of a new 6.0 meV mode not previously reported or predicted.

Abstract

In this letter we report results from inelastic neutron scattering experiments on powder samples of vanadyl pyrophosphate, (VO)2P2O7. We see evidence for three magnetic excitations, at 3.5 meV, 6.0 meV and 14 meV. The intensity of the 3.5 meV mode is strong near Q=0.8 A-1, consistent with the one-magnon gap mode reported previously and predicted by the spin-ladder model. The magnetic scattering at 14 meV may be due to the top of the one-magnon band or the two-magnon continuum predicted in the ladder model. The 6.0 meV mode also peaks in intensity at Q=0.8 A-1. This mode has not been reported previously and was not anticipated by existing theoretical treatments of the spin ladder.