Two-dimensional (2D) magnetic ferrovalley materials, with both spontaneous spin and valley polarization properties, have attracted significant attention due to their potential applications in spintronics and valley electronics. Herein, using first-principles calculation, we predict a new stable ferromagnetic (FM) semiconductor, PrBr₂ monolayer (ML), which is demonstrated as a ferrovalley material. PrBr₂ ML has excellent mechanical, dynamic, and thermal stabilities. Its intrinsic FM ground state has a large magnetic anisotropy energy (MAE) of 130 μeV and a higher Curie temperature (T_C) of 101 K compared to those of the synthesized FM 2D materials. Owing to the interplay of magnetic exchange and spin–orbit coupling, it has sizable valley polarization, reaching up to 55 meV. The values of Berry curvature between the K and −K valleys are opposite, giving rise to an anomalous valley Hall effect. Furthermore, an enhancement of both MAE and valley polarization can be induced by applying modest tensile biaxial strains. Remarkably, the magnetization easy axis can translate from in-plane to out-of-plane orientation as the compressive strain is less than −5%. These findings not only highlight the significant role of strains in tuning the spin- and valley-relevant properties but also establish a promising FM ferrovalley semiconducting candidate for spintronic and valleytronic devices.

中文翻译：

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应变下铁磁PrBr2单分子层谷极化的第一性原理研究

二维（2D）磁性铁谷材料具有自发自旋和谷极化特性，由于其在自旋电子学和谷电子学中的潜在应用而引起了人们的广泛关注。在这里，利用第一性原理计算，我们预测了一种新的稳定铁磁（FM）半导体，PrBr ₂单层（ML），它被证明是一种铁谷材料。 PrBr ₂ ML 具有优异的机械稳定性、动态稳定性和热稳定性。与合成的 FM 2D 材料相比，其本征 FM 基态具有 130 μeV 的大磁各向异性能量 (MAE) 和 101 K 的更高居里温度 ( _TC ) 。由于磁交换和自旋轨道耦合的相互作用，它具有相当大的谷极化，高达 55 meV。 K 谷和 −K 谷之间的贝里曲率值相反，产生反常谷霍尔效应。此外，通过施加适度的拉伸双轴应变可以诱导 MAE 和谷极化的增强。值得注意的是，当压缩应变小于-5%时，易磁化轴可以从面内方向转变为面外方向。这些发现不仅强调了应变在调节自旋和谷相关特性方面的重要作用，而且还为自旋电子和谷电子器件建立了一种有前景的调频铁谷半导体候选材料。