Two-dimensional (2D) intrinsic ferromagnetic semiconductors (FMSs) received huge attention due to their fascinating electron charge and spin properties, which are promising candidates for spintronic devices. In this work, we propose a class of monolayer FMS in alkali-based chromium chalcogenides (XCrY₂, X = Li and Na; Y = S, Se, and Te). The proposed monolayer XCrY₂ is expected to be exfoliated from their corresponding bulk counterparts, which are confirmed by first-principles calculations. Our calculations indicate that these monolayer FMS shows the ferromagnetic ground states possessing the high Curie temperatures using the Ising and Heisenberg models. The hybrid functional calculations show that LiCrSe₂, NaCrSe₂, and NaCrTe₂ have desirable direct band gaps. In addition, it is found that the spin–orbit (SOC) effect can tremendously change the effective mass of the holes, resulting in higher hole mobility (up to 3 × 10³ cm² v^–1 s^–1). Our study provides a feasible way to realize 2D intrinsic FMS.

中文翻译：

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二维碱基铬硫属元素化物中的本征铁磁半导体

二维（2D）本征铁磁半导体（FMS）由于其引人入胜的电子电荷和自旋特性而备受关注，这是自旋电子器件的有希望的候选者。在这项工作中，我们提出了一类在碱基铬硫属元素化物中的单层FMS（XCrY ₂，X = Li和Na； Y = S，Se和Te）。拟议的单层XCrY ₂有望从其相应的本体中剥离，并通过第一性原理计算得到证实。我们的计算表明，使用Ising和Heisenberg模型，这些单层FMS显示出具有高居里温度的铁磁基态。混合函数计算表明，LiCrSe ₂，NaCrSe ₂和NaCrTe₂具有理想的直接带隙。另外，发现自旋轨道（SOC）效应可以极大地改变孔的有效质量，从而导致更高的孔迁移率（高达3×10 ³ cm ² v ^–1 s ^–1）。我们的研究提供了一种实现二维固有FMS的可行方法。