论文标题
从磁性lifepo $ _4 $中的自旋波激发的磁场依赖性磁场依赖性的精炼磁相互作用
Refining magnetic interactions from the magnetic field dependence of spin-wave excitations in magnetoelectric LiFePO$_4$
论文作者
论文摘要
我们调查了磁性$ \ text {lifepo} _4 $ thz吸收光谱的旋转激发，最高33 $ \，$ t。通过研究他们的选择规则，我们不仅发现磁极，而且还发现电动 - 电动偶极（电磁）和磁电共振。我们的四个强烈的低能模式的磁场依赖性通过我们沿三个正骨轴施加的场的四个公共旋转模型很好地重现了。从拟合中，我们完善了交换耦合，单离子各向异性和dzyaloshinskii-Moriya相互作用参数。在较高的频率下观察到平均场模型未描述的其他自旋激发。其中一些显示了磁场的强烈转移，最多4 $ \，\ text {cm}^{ - 1}/\ text {t} $，沿易于轴应用该字段时。基于此磁场依赖性，我们将这些高频共振归因于较高的自旋多物和两个镁的激发，它们由于磁有序状态的低对称性而变得活跃。
We investigated the spin excitations of magnetoelectric $\text{LiFePO}_4$ by THz absorption spectroscopy in magnetic fields up to 33$\,$T. By studying their selection rules, we found not only magnetic-dipole, but also electric-dipole active (electromagnons) and magnetoelectric resonances. The magnetic field dependence of four strong low-energy modes is reproduced well by our four-sublattice spin model for fields applied along the three orthorhombic axes. From the fit, we refined the exchange couplings, single-ion anisotropies, and the Dzyaloshinskii-Moriya interaction parameters. Additional spin excitations not described by the mean-field model are observed at higher frequencies. Some of them shows a strong shift with magnetic field, up to 4$\,\text{cm}^{-1}/\text{T}$, when the field is applied along the easy axis. Based on this field dependence, we attribute these high frequency resonances to excitation of higher spin multipoles and of two magnons, which become THz-active due to the low symmetry of the magnetically ordered state.
