Polarized Raman scattering in magnetoelectric ${\mathrm{LiNiPO}}_4$ shows a sharp resonant peak at 37 ${\mathrm{cm}}^{-1}$ in the magnetically ordered phase, originating from a one-magnon excitation of ${\mathrm{Ni}}^{2+}S=1$ localized moments at the zone center. Also, a broad component with maximum intensity at $\sim 65{\mathrm{cm}}^{-1}$ is observed and successfully modeled in terms of light scattering from two-magnon excitations within the framework of the Fleury-Loudon theory using five relevant exchange parameters, providing an independent experimental confirmation of their values previously obtained with inelastic neutron scattering data in this material. An additional peak at 58 ${\mathrm{cm}}^{-1}$, already reported in previous works, shows no detectable Zeeman splitting for magnetic fields up to 6 T along the crystallographic a and c directions, excluding one-magnon scattering as a possible assignment for this peak. The possible nature of this excitation is discussed.

中文翻译：

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LiNiPO4磁电中一个和两个磁振子的拉曼散射

磁电中的极化拉曼散射 ${\mathrm{磷酸锂}}_4$ 在37处显示一个尖锐的共振峰 ${\mathrm{厘米}}^{-\mathrm{1个}}$ 在磁有序相中，源于 ${你}^{2+}\mathrm{小号}=\mathrm{1个}$在区域中心的局部时刻。另外，在$〜\mathrm{65岁}{\mathrm{厘米}}^{-\mathrm{1个}}$在Fleury-Loudon理论的框架内，使用五个相关的交换参数，观察到并成功地对来自两磁振子激发的光散射进行了建模，从而提供了独立的实验证实，该值先前是使用该材料中的非弹性中子散射数据获得的。在58处达到另一个峰值${\mathrm{厘米}}^{-\mathrm{1个}}$在先前的工作中已经报道过，显示沿晶体学a和c方向对高达6 T的磁场没有可检测到的塞曼分裂，不包括单磁子散射作为该峰的可能赋值。讨论了这种激发的可能性质。