Key Laboratory for the Physics and Chemistry of Nanodevices, Department of Electronics, Peking University, Beijing 100871, China.
Phys Chem Chem Phys. 2010 Sep 28;12(36):10805-11. doi: 10.1039/c002301a. Epub 2010 Jul 23.
The spin transport properties of a series of 3d transition metal(ii) phthalocyanines (MPc, M = Mn, Fe, Co, Ni, Cu and Zn) sandwiched between two semi-infinite armchair single-walled carbon nanotube electrodes are investigated by using a self-consistent ab initio approach that combines the non-equilibrium Green's function formalism with spin density functional theory. Our calculations show that among the six molecules only MnPc and FePc can act as nearly perfect spin filters and at the same time have a large transmission around the Fermi level. This is dominated by the highest occupied molecular orbital (HOMO) of the corresponding MPc molecule. In contrast to the other four MPc molecules, whose HOMO is the a(1u) orbital located over the Pc ring, the HOMO of MnPc and FePc is a doubly degenerate pi-type orbital composed of the 3d(xz) and 3d(yz) atomic orbitals of the metal center. The spin polarization of MnPc and FePc is independent of the size of the SWCNT electrodes and can be tuned by chemisorption at the metal center, demonstrating that MPc and carbon nanotubes are a promising materials platform for applications in molecular spintronics.
一系列 3d 过渡金属(ii)酞菁（MPc，M=Mn、Fe、Co、Ni、Cu 和 Zn）夹在两个半无限扶手椅单壁碳纳米管电极之间的自旋输运性质，通过使用自洽的从头算方法进行了研究，该方法将非平衡格林函数形式与自旋密度泛函理论相结合。我们的计算表明，在这六种分子中，只有 MnPc 和 FePc 可以作为近乎完美的自旋滤波器，并且在费米能级附近具有较大的传输率。这主要由相应的 MPc 分子的最高占据分子轨道（HOMO）决定。与其他四个 MPc 分子不同，它们的 HOMO 是位于 Pc 环上的 a(1u)轨道，MnPc 和 FePc 的 HOMO 是由金属中心的 3d(xz)和 3d(yz)原子轨道组成的简并 pi 型轨道。MnPc 和 FePc 的自旋极化与 SWCNT 电极的大小无关，并且可以通过金属中心的化学吸附进行调节，这表明 MPc 和碳纳米管是分子自旋电子学应用的有前途的材料平台。
