Department of Physics, Pukyong National University, Busan, Korea.
J Phys Condens Matter. 2010 Dec 8;22(48):486006. doi: 10.1088/0953-8984/22/48/486006. Epub 2010 Nov 16.
Using the full potential linearized augmented plane wave (FLAPW) method, we have explored the magnetic properties of ultrathin C and N layers on a MgO(001) surface. It has been found that the free standing C layer has a ferromagnetic (FM) ordering with a magnetic moment of 0.82 μ(B), while the free standing N layer with the same coverage displays an antiferromagnetic (AFM) state with a magnetic moment of 1.68 μ(B). Through a structure optimization procedure, we have found that both C and N adatoms are adsorbed on the O-top position in the presence of a MgO(001) surface. The ultrathin 0.25 monolayer coverage of C/MgO(001) film becomes a magnetic semiconductor and shows the c(2 × 2) AFM ground state with a magnetic moment of 0.62 μ(B). Surprisingly, the ultrathin N/MgO(001) manifests a half metallic state with a magnetic moment of 0.47 μ(B). In addition, the induced spin polarization in the O atom is found and this hybridization significantly affects the density of states (DOS) behavior. This peculiar DOS feature results in the opposite magnetic ground states of C and N layers on a MgO(001) surface. Additionally, it is found that the N/MgO(001) has a perpendicular magnetocrystalline anisotropy energy of 63 µeV. We also present theoretically calculated x-ray absorption spectroscopy (XAS) and x-ray magnetic circular dichroism (XMCD) results.
利用完全势线性缀加平面波（FLAPW）方法，我们研究了 MgO（001）表面上的超薄 C 和 N 层的磁性。研究发现，自由站立的 C 层具有铁磁（FM）有序，磁矩为 0.82μB，而具有相同覆盖度的自由站立的 N 层显示出反铁磁（AFM）状态，磁矩为 1.68μB。通过结构优化过程，我们发现 C 和 N adatoms 在 MgO（001）表面存在的情况下都被吸附在 O 顶端位置。超薄的 0.25 单层 C/MgO（001）薄膜覆盖层成为磁性半导体，并显示出 c（2×2） AFM 基态，磁矩为 0.62μB。令人惊讶的是，超薄的 N/MgO（001）呈现出半金属状态，磁矩为 0.47μB。此外，在 O 原子中发现了诱导自旋极化，这种杂化显著影响了态密度（DOS）行为。这种特殊的 DOS 特征导致了 MgO（001）表面上 C 和 N 层的相反的磁基态。此外，还发现 N/MgO（001）具有 63μeV 的垂直磁晶各向异性能量。我们还呈现了理论计算的 X 射线吸收光谱（XAS）和 X 射线磁圆二色性（XMCD）结果。
