By utilizing symmetry analysis and electronic structure calculations, we investigated the low-temperature orthorhombic phase of ${\mathrm{Ag}}_2\mathrm{Se}$ in $\mathcal{SG}$ 17. In addition to the discovery of a nodal plane at $k_z=\pi$ protected by the joint operation of time reversal ($\mathcal{T}$) and the twofold screw rotation $S_{2z}$, we found 24 Weyl points mainly residing at the $k_y=0$ plane with notable Fermi arc and large quasiparticle interference pattern (QPI). Due to the absence of mirror symmetry, a pair of Weyl points with opposite chirality reside at different binding energies, which makes this system an excellent material candidate for realizing the novel chiral anomaly related phenomenon, such as the quantized circular photogalvanic and the chiral magnetic effects. Furthermore, we also reveal the striking spin textures at $k_z=\pi$ plane which demonstrates, in a large region of the surface Brillouin zone, a direction-selective spin polarization, which has a strong implication to spintronic applications.

中文翻译：

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Weyl半金属中无镜面对称的节点面和持续自旋织构

通过利用对称分析和电子结构计算，我们研究了低温的正交晶相。 ${银}_2硒$ 在 $\mathcal{SG}$ 17.除了在 ${ķ}_{ž}=\pi$ 受时间反转联合操作的保护（$\mathcal{Ť}$）和双重螺丝旋转 ${\mathrm{小号}}_{2ž}$，我们发现24个Weyl点主要位于 ${ķ}_{ÿ}=0$费米弧明显且准粒子干涉图样（QPI）大的平面。由于没有镜像对称性，一对具有相反手性的Weyl点位于不同的结合能上，这使得该系统成为实现新型手性异常相关现象（例如定量圆形光电动势和手性磁效应）的极佳材料候选。此外，我们还揭示了惊人的自旋纹理${ķ}_{ž}=\pi$ 该平面在布里渊区的大部分区域表现出方向选择性的自旋极化，这对自旋电子学应用具有重要意义。