Valleytronics has gradually attracted people's attention for providing new degrees of freedom to future electronic devices. Herein, it is proposed that valley polarization can be realized in 2D ferromagnetic FeCl with a square lattice. The first‐principles calculations without spin–orbital coupling (SOC) show that 2D FeCl is a spin‐polarized semimetal material, and the crossing points around the Fermi level are protected by mirror symmetry. When considering SOC, local bandgaps open around the Fermi level, and further calculations reveal that the Berry curvatures are opposite in sign around these gaps along with different high‐symmetry directions. By integrating the Berry curvature around these local extreme points, the Chern numbers of two valleys are ≈ −1/4 and 1/4, respectively, and the corresponding valley Chern number C_v is approximately equal to 1/2. This indicates that FeCl has the potential to realize the valley Hall effect (VHE) and will be a promising material in future valleytronics.

中文翻译：

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单层铁磁性FeCl中的谷底极化：第一性原理研究

Valleytronics已为未来的电子设备提供新的自由度而逐渐引起人们的关注。在此，提出可以在具有方晶格的二维铁磁性FeCl中实现谷极化。没有自旋-轨道耦合（SOC）的第一性原理计算表明，二维FeCl是自旋极化的半金属材料，费米能级附近的交点受到镜面对称的保护。考虑SOC时，局部带隙在费米能级附近打开，进一步的计算表明，在这些间隙周围，浆果曲率在符号上是相反的，并且具有不同的高对称方向。通过对这些局部极点周围的Berry曲率进行积分，两个谷的Chern数分别为≈-1/4和1/4，以及相应的谷Chern数C _v大约等于1/2。这表明FeCl具有实现谷底霍尔效应（VHE）的潜力，并将成为未来Valleytronics的有前途的材料。