Coexistence of dimerization and long-range magnetic order in the quantum antiferromagnetic compound LiCu2O2: inelastic light scattering study

摘要

Raman scattering studies of the frustrated spin chain systemLiCu$_{2}$O$_{2}$ are reported. Two transitions into a magnetically orderedphase (taken place at temperatures $\sim$ 9 K and $\sim$ 24 K) have beenconfirmed from the analysis of optical properties of the samples.Interestingly, two different magnetic excitations, seen at 100 and 110cm$^{-1}$ in the magnetically ordered phase superimpose each otherindependently, indicating a coherent coexistence of long-range magnetic orderand dimerization. The observed phenomenon is attributed to magnetostructuralpeculiarities of LiCu$_{2}$O$_{2}$ leading to the intrinsic presence ofnonmagnetic impurities on a nanometer scale. Furthermore, magnetic impuritiesplay a significant role in driving the transition from an incommensurate stateto a N\'{e}el ordered one at 9 K.