Wang Shiyao, Wang Junjie, Khazaei Mohammad
State Key Laboratory of Solidification Processing, Northwestern Polytechnical University, Xi'an, Shaanxi 710072, People's Republic of China.
Phys Chem Chem Phys. 2020 May 28;22(20):11731-11739. doi: 10.1039/d0cp01767a. Epub 2020 May 15.
Two-dimensional (2-D) antiferromagnetic (AFM) materials have shown promise over their ferromagnetic (FM) counterparts for developing advanced spintronic devices; however, they have been rarely found with high Néel temperatures to date. Here, by employing first-principles calculations and Monte Carlo simulations, we demonstrate that the family of 2-D iron oxyhalides monolayers, FeOX (X = F, Cl, Br, I), are magnetic Mott insulators with their AFM ground state possessing relatively high Néel temperatures. The structural stabilities of the FeOX monolayers are proved using a set of phonon, molecular dynamics, and elastic constant calculations. The calculated Néel temperature of the FeOCl monolayer is close to that of FeOCl bulk because of the weak van der Waals interaction between the layers. More importantly, the predicted Néel temperatures of FeOX (X = F, Cl, Br, I) monolayers can be increased by biaxial compression strain. The Néel temperature of the strained FeOF and FeOI monolayers can approach 200 K, which suggests that they can be robust antiferromagnets with relatively high Néel temperatures compared with other available 2-D magnets. Our calculations show that both the in-plane and the inter-plane magnetic interactions affect the AFM coupling between Fe atoms in FeOX monolayers. The easy axis of the 2-D FeOX is found to be along the in-plane direction. The FeOX monolayers may provide an excellent platform for building novel spintronic devices at the nanoscale.
二维（2-D）反铁磁（AFM）材料在开发先进自旋电子器件方面比其铁磁（FM）对应物更具前景；然而，迄今为止很少发现它们具有高奈尔温度。在此，通过采用第一性原理计算和蒙特卡罗模拟，我们证明二维铁卤氧化物单层FeOX（X = F、Cl、Br、I）家族是磁性莫特绝缘体，其反铁磁基态具有相对较高的奈尔温度。通过一组声子、分子动力学和弹性常数计算证明了FeOX单层的结构稳定性。由于层间范德华相互作用较弱，计算得到的FeOCl单层的奈尔温度与FeOCl块体相近。更重要的是，FeOX（X = F、Cl、Br、I）单层的预测奈尔温度可以通过双轴压缩应变提高。应变的FeOF和FeOI单层的奈尔温度可以接近200 K，这表明与其他现有的二维磁体相比，它们可以是具有相对较高奈尔温度的稳健反铁磁体。我们的计算表明，面内和面间磁相互作用都影响FeOX单层中Fe原子之间的反铁磁耦合。发现二维FeOX的易轴沿面内方向。FeOX单层可能为在纳米尺度构建新型自旋电子器件提供一个极好的平台。
