Li Xiao-Fei, Liu Lingling, Yan Qing, Li Qin-Kun, Wang Yunxiang, Deng Mingsen, Qiu Qi
School of Optoelectronic Information, University of Electronic Science and Technology of China, Chengdu, Sichuan 610054, China.
Guizhou Synergetic Innovation Center of Scientific Big Data for Advanced Manufacturing Technology, Guizhou Education University, Guiyang, 550018, China.
Phys Chem Chem Phys. 2017 Jan 25;19(4):2674-2678. doi: 10.1039/c6cp08357a.
Ferromagnetic devices have special significance in spintronics. Here, we investigate the electronic structures and transport properties of the experimentally achievable FeN-embedded armchair and zigzag graphene nanoribbons (FeN-AGNR and FeN-ZGNR). The first principles results show that FeN induces room-temperature stable ferromagnetic ground states in both AGNRs and ZGNRs, but only significant changes in the band structure of the latter, inducing strong current polarization (nearly 100%) and spin-dependent negative differential resistance (NDR) in the FeN-ZGNR based devices. We find that the performance of the NDR can be easily enhanced by embedding more FeN structures. Its peak-to-valley current ratio (PVCR) rises rapidly and reaches 10 when only 4 FeN structures are used. It is revealed that the localized f electrons of the Fe atom and the p electrons of the C atoms at the ribbon edges have the same spin orientation, resulting in a ferromagnetic ground state with a larger magnetic moment, FeN induces conductive states around the Fermi level, which are responsible for the observed NDR, and the quite different conductivity of the frontier orbitals in the spin-down and spin-down systems contributes to the strong current polarization. Such intrinsic properties suggest prospective device applications of the FeN-ZGNRs in spintronics.
铁磁器件在自旋电子学中具有特殊意义。在此，我们研究了实验上可实现的嵌入FeN的扶手椅型和锯齿型石墨烯纳米带（FeN-AGNR和FeN-ZGNR）的电子结构和输运性质。第一性原理结果表明，FeN在AGNR和ZGNR中均诱导出室温稳定的铁磁基态，但仅对后者的能带结构产生显著变化，在基于FeN-ZGNR的器件中诱导出强电流极化（近100%）和自旋相关的负微分电阻（NDR）。我们发现，通过嵌入更多的FeN结构可以轻松提高NDR的性能。当仅使用4个FeN结构时，其峰谷电流比（PVCR）迅速上升并达到10。结果表明，Fe原子的局域f电子与纳米带边缘C原子的p电子具有相同的自旋取向，从而导致具有更大磁矩的铁磁基态，FeN在费米能级附近诱导出导电态，这是观察到的NDR的原因，并且自旋向下和自旋向上系统中前沿轨道的电导率差异很大，这导致了强电流极化。这些本征特性表明FeN-ZGNR在自旋电子学中具有潜在的器件应用前景。
