Magnetic Properties of (VO)_2P_2O_7 from Frustrated Interchain Coupling

TL;DR

This paper investigates the magnetic properties of (VO)_2P_2O_7, revealing a frustrated interchain coupling that explains complex magnon behaviors and introduces a minimal model matching experimental observations.

Contribution

It introduces a minimal frustrated coupling model for (VO)_2P_2O_7 that accurately explains magnon dispersion, susceptibility, and ESR data, highlighting the role of frustration.

Findings

Identification of a gapped magnon dispersion and a low-lying second mode

Development of a minimal frustrated coupling model that fits experimental data

Proposal that two-magnon bound states explain the second mode

Abstract

Neutron-scattering experiments on (VO)_2P_2O_7 reveal both a gapped magnon dispersion and an unexpected, low-lying second mode. The proximity and intensity of these modes suggest a frustrated coupling between the alternating spin chains. We deduce the minimal model containing such a frustration, and show that it gives an excellent account of the magnon dispersion, static susceptibility and electron spin resonance absorption. We consider two-magnon states which bind due to frustration, and demonstrate that these may provide a consistent explanation for the second mode.