National Synchrotron Radiation Laboratory, University of Science and Technology of China , Hefei, Anhui 230029, People's Republic of China.
ACS Nano. 2014 Oct 28;8(10):10589-96. doi: 10.1021/nn5040845. Epub 2014 Sep 17.
Control over the magnetic interactions in dilute magnetic semiconductor quantum dots (DMSQDs) is a key issue to future development of nanometer-sized integrated "spintronic" devices. However, manipulating the magnetic coupling between impurity ions in DMSQDs remains a great challenge because of the intrinsic quantum confinement effects and self-purification of the quantum dots. Here, we propose a hybrid structure to achieve room-temperature ferromagnetic interactions in DMSQDs, via engineering the density and nature of the energy states at the Fermi level. This idea has been applied to Co-doped ZnO DMSQDs where the growth of a reduced graphene oxide shell around the Zn(0.98)Co(0.02)O core turns the magnetic interactions from paramagnetic to ferromagnetic at room temperature, due to the hybridization of 2p(z) orbitals of graphene and 3d obitals of Co(2+)-oxygen-vacancy complexes. This design may open up a kind of possibility for manipulating the magnetism of doped oxide nanostructures.
控制稀磁半导体量子点（DMSQDs）中的磁相互作用是未来纳米级集成“自旋电子”器件发展的关键问题。然而，由于量子点的固有量子限制效应和自净化作用，操纵 DMSQDs 中杂质离子之间的磁耦合仍然是一个巨大的挑战。在这里，我们通过工程化费米能级处的态密度和态性质，提出了一种混合结构，以实现 DMSQDs 中的室温铁磁性相互作用。这一想法已应用于 Co 掺杂 ZnO DMSQDs 中，由于在 Zn(0.98)Co(0.02)O 核周围生长的还原氧化石墨烯壳层，由于石墨烯的 2p(z)轨道和 Co(2+)-氧空位复合物的 3d 轨道的杂化，使磁相互作用从顺磁变为室温铁磁。这种设计可能为操纵掺杂氧化物纳米结构的磁性开辟了一种可能性。
