Half-Unit-Cell α-Fe2O3 Semiconductor Nanosheets with Intrinsic and Robust Ferromagnetism
Half-Unit-Cell α-Fe2O3 Semiconductor Nanosheets with Intrinsic and Robust Ferromagnetism
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DOI：
10.1021/ja504088n
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发表时间：
2014-07-23
影响因子：
15
通讯作者：
Wei, Shiqiang
中科院分区：
文献类型：
--
作者：
Cheng, Weiren;He, Jingfu;Wei, Shiqiang
原子级薄的过渡金属氧化物纳米片作为一类全新概念的材料，对于下一代电子和磁性纳米器件的发展具有重要意义，但仍然是化学和物理方面的一项根本性挑战。在此，基于“模板辅助定向生长”策略，我们成功合成了典型过渡金属氧化物α - Fe₂O₃的半单胞纳米片，其在100 K时展现出0.6 μB/原子的强本征铁磁性，并在室温下仍保持铁磁性。X射线吸收光谱显示出一种独特的表面结构畸变，产生了不同的铁离子环境，并导致铁离子链的距离波动。第一性原理计算表明，铁3d能态量子简并的有效打破激活了这些Fe₅ - co - O - Fe₆ - co离子链中的铁磁交换相互作用。这些结果为调整自旋交换相互作用提供了坚实的设计原则，并为未来的半导体自旋电子学带来了希望。
The synthesis of atomically thin transitionmetal oxide nanosheets as a conceptually new class of materials is significant for the development of next-generation electronic and magnetic nanodevices but remains a fundamental chemical and physical challenge. Here, based on a "template-assisted oriented growth" strategy, we successfully synthesized half-unit-cell nanosheets of a typical transition-metal oxide alpha-Fe2O3 that show robust intrinsic ferromagnetism of 0.6 mu(B)/atom at 100 K and remain ferromagnetic at room temperature. A unique surface structure distortion, as revealed by X-ray absorption spectroscopy, produces nonidentical Fe ion environments and induces distance fluctuation of Fe ion chains. First-principles calculations reveal that the efficient breaking of the quantum degeneracy of Fe 3d energy states activates ferromagnetic exchange interaction in these Fe5-co-O-Fe6-co ion chains. These results provide a solid design principle for tailoring the spin-exchange interactions and offer promise for future semiconductor spintronics.