First-principles electronic-structure calculations have been employed to investigate the Rashba-Dresselhaus spin splitting of bands in the recently predicted ferroelectric nitride perovskite ${\mathrm{LaWN}}_3$. Our first-principles results are supplemented with an effective $\mathbf{k}·\mathbf{p}$ model analysis. A systematic study of orthorhombic and rhombohedral phases of this system reveals the importance of symmetry in realizing the nature of the splitting of bands around the time-reversal invariant $k$ points. Orthorhombic ${\mathrm{LaWN}}_3$ shows linear Rashba-Dresselhaus splitting where nonsymmorphic symmetries play an important role in enhancing the band splitting in the $k_z=\pi /c$ plane, while the rhombohedral phase shows the existence of a unique higher order Rashba-Dresselhaus term which mixes with the linear Rashba-Dresselhaus term to produce an unusual pattern of out-of-plane spin components in the spin texture.

中文翻译：

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氮化铁钙钛矿LaWN3中Rashba-Dresselhaus效应的起源

第一性原理电子结构计算已用于研究最近预测的铁电氮化物钙钛矿中带的Rashba-Dresselhaus自旋分裂 ${\mathrm{草坪}}_3$。我们的第一原理结果得到有效补充$\mathbf{ķ}·\mathbf{p}$模型分析。对该系统的正交相和菱面体相的系统研究表明，对称性在实现时间逆不变性周围的频带分裂的本质方面很重要$ķ$点。斜方晶${\mathrm{草坪}}_3$ 展示了线性Rashba-Dresselhaus分裂，其中非对称对称在增强带内分裂方面起着重要作用。 ${ķ}_{ž}=\pi /C$ 平面，而菱面体相则显示存在唯一的高阶Rashba-Dresselhaus项，该项与线性Rashba-Dresselhaus项混合产生自旋纹理中平面外自旋分量的异常模式。