Hu Y, Liu X Y, Shen Z H, Luo Z F, Chen Z G, Fan X L
State Key Laboratory of Solidification Processing, Center for Advanced Lubrication and Seal Materials, School of Material Science and Engineering, Northwestern Polytechnical University, 127 YouYi Western Road, Xi'an, Shaanxi 710072, China.
Nanoscale. 2020 Jun 7;12(21):11627-11637. doi: 10.1039/c9nr10927g. Epub 2020 May 21.
Two-dimensional (2D) magnets with room temperature ferromagnetism and semiconductors with moderate band gap and high carrier mobility are highly desired for applications in nanoscale electronics and spintronics. By performing the first-principles calculations, we investigate novel Fe, Co, Ni carbide based pristine (MC) and functionalized (MCT, T: F, O, OH) MXenes. Our calculations show that FeC, CoC, NiC, FeCF, FeCO, FeC(OH), CoCF, CoC(OH) and NiCF are dynamically and mechanically stable. More importantly, FeC, CoC, FeCF and FeC(OH) exhibit intrinsic ferromagnetism (magnetic moments 2-5μ per unit cell). Monte Carlo simulations suggest high Curie temperatures of 590 and 920 K for FeC and FeCF, respectively, at the HSE06 level owing to the large spin magnetic moments and strong ferromagnetic coupling. Based on the deformation potential theory, we predict high and anisotropic hole mobility (0.2-1.4 × 10 cm V s) for semiconducting FeCO and CoC(OH). Additionally, NiCF demonstrates highly anisotropic electron mobility together with a direct band gap. Our results further show the effectiveness of surface functionalization in modulating the electronic and magnetic properties and broadening the properties of MXenes to achieve long-range intrinsic ferromagnetism well above room temperature and high carrier mobility.
具有室温铁磁性的二维（2D）磁体以及具有适度带隙和高载流子迁移率的半导体在纳米级电子学和自旋电子学应用中具有很高的需求。通过进行第一性原理计算，我们研究了基于新型铁、钴、镍碳化物的原始（MC）和功能化（MCT，T：F、O、OH）MXenes。我们的计算表明，FeC、CoC、NiC、FeCF、FeCO、FeC(OH)、CoCF、CoC(OH)和NiCF在动力学和力学上是稳定的。更重要的是，FeC、CoC、FeCF和FeC(OH)表现出本征铁磁性（每个晶胞的磁矩为2 - 5μ）。蒙特卡罗模拟表明，由于大的自旋磁矩和强铁磁耦合，在HSE06水平下，FeC和FeCF的居里温度分别高达590 K和920 K。基于形变势理论，我们预测半导体FeCO和CoC(OH)具有高且各向异性的空穴迁移率（0.2 - 1.4×10 cm² V⁻¹ s⁻¹）。此外，NiCF表现出高度各向异性的电子迁移率以及直接带隙。我们的结果进一步表明了表面功能化在调节电子和磁性特性以及拓宽MXenes的特性以实现远高于室温的长程本征铁磁性和高载流子迁移率方面的有效性。
