Hod Oded, Barone Verónica, Peralta Juan E, Scuseria Gustavo E
Department of Chemistry, Rice University, Houston, Texas 77005-1892, USA.
Nano Lett. 2007 Aug;7(8):2295-9. doi: 10.1021/nl0708922. Epub 2007 Jul 12.
We present a comprehensive theoretical study of the electronic properties and relative stabilities of edge-oxidized zigzag graphene nanoribbons. The oxidation schemes considered include hydroxyl, lactone, ketone, and ether groups. Using screened exchange density functional theory, we show that these oxidized ribbons are more stable than hydrogen-terminated nanoribbons except for the case of the etheric groups. The stable oxidized configurations maintain a spin-polarized ground state with antiferromagnetic ordering localized at the edges, similar to the fully hydrogenated counterparts. More important, edge oxidation is found to lower the onset electric field required to induce half-metallic behavior and extend the overall field range at which the systems remain half-metallic. Once the half-metallic state is reached, further increase of the external electric field intensity produces a rapid decrease in the spin magnetization up to a point where the magnetization is quenched completely. Finally, we find that oxygen-containing edge groups have a minor effect on the energy difference between the antiferromagnetic ground state and the above-lying ferromagnetic state.
我们对边缘氧化的锯齿形石墨烯纳米带的电子性质和相对稳定性进行了全面的理论研究。所考虑的氧化方案包括羟基、内酯、酮和醚基。使用筛选交换密度泛函理论，我们表明，除了醚基的情况外，这些氧化带比氢终止的纳米带更稳定。稳定的氧化构型保持自旋极化基态，反铁磁有序定域在边缘，类似于完全氢化的对应物。更重要的是，发现边缘氧化降低了诱导半金属行为所需的起始电场，并扩展了系统保持半金属状态的整体场范围。一旦达到半金属状态，外部电场强度的进一步增加会导致自旋磁化强度迅速下降，直至磁化强度完全淬灭。最后，我们发现含氧基边缘基团对反铁磁基态与上方铁磁态之间的能量差影响较小。
