Key Laboratory of Physics and Technology for Advanced Batteries (Ministry of Education), Department of Physics, Jilin University, Changchun 130012, China.
Phys Chem Chem Phys. 2018 Nov 14;20(44):28162-28168. doi: 10.1039/c8cp05467c.
As a promising candidate suitable for applications in spintronic devices at the nanoscale and in high-density data storage, two-dimensional (2D) intrinsic ferromagnetic materials with magnetic anisotropy (MA) have been experimentally demonstrated in the last year. Monolayer RuO2 and OsO2 hold great potential for achieving large MA due to the strong spin-orbit coupling (SOC) interactions of Ru and Os. Using first-principles calculations, we systematically investigate the stability, electronic structure and magnetic properties of monolayer 1T-RuO2 and 1T-OsO2 and explore the effects of strain on their electronic structure and magnetic properties. It is found that both monolayer 1T-RuO2 and 1T-OsO2 are 2D intrinsic ferromagnetic materials with large MA. In particular, the magnetic anisotropy energy (MAE) of monolayer 1T-OsO2 is as high as -42.67 meV per unit cell and its Curie temperature is much higher than the liquid-nitrogen temperature. It is worth noting that the large MA of monolayer 1T-OsO2 is significantly enhanced by tensile strain. By analyzing the density of states and the d orbital-resolved MAE of Os and Ru atoms based on second-order perturbation theory, it is revealed that the large MAE of monolayer 1T-RuO2 and 1T-OsO2 is mainly contributed by the matrix element differences between the opposite-spin dxy and dx2-y2 orbitals of Ru and Os atoms, and the tensile strain induced enhancement of monolayer 1T-OsO2 mainly originates from the change in contributions to the MA from the matrix element differences between the dyz and dz2 orbitals of Os atoms from zero to negative. Our results indicate that monolayer 1T-RuO2 and especially monolayer 1T-OsO2 are promising candidates suitable for applications in spintronic devices at the nanoscale and in high-density data storage.
作为一种有前途的候选材料，适用于纳米尺度的自旋电子器件和高密度数据存储，具有磁各向异性（MA）的二维（2D）本征铁磁材料在过去一年中已经得到了实验验证。单层 RuO2 和 OsO2 由于 Ru 和 Os 的强自旋轨道耦合（SOC）相互作用，具有实现大 MA 的巨大潜力。使用第一性原理计算，我们系统地研究了单层 1T-RuO2 和 1T-OsO2 的稳定性、电子结构和磁性质，并探讨了应变对其电子结构和磁性质的影响。结果发现，单层 1T-RuO2 和 1T-OsO2 均为 2D 本征铁磁材料，具有较大的 MA。特别是，单层 1T-OsO2 的磁各向异性能（MAE）高达-42.67 meV/单位胞，其居里温度远高于液氮温度。值得注意的是，单层 1T-OsO2 的大 MA 可以通过拉伸应变得到显著增强。通过基于二阶微扰理论分析了 Os 和 Ru 原子的态密度和 d 轨道分辨 MAE，揭示了单层 1T-RuO2 和 1T-OsO2 较大的 MAE 主要来源于 Ru 和 Os 原子的相反自旋 dxy 和 dx2-y2 轨道的矩阵元差，而拉伸应变引起的单层 1T-OsO2 的增强主要源于 Os 原子的 dyz 和 dz2 轨道的矩阵元差对 MA 的贡献从 0 变为负值。我们的结果表明，单层 1T-RuO2 和特别是单层 1T-OsO2 是适用于纳米尺度的自旋电子器件和高密度数据存储的有前途的候选材料。
