A deft technique allows magnetic atoms to be placed one by one in a semiconductor crystal. It's a further step towards an ambitious goal: a computer chip that might simultaneously store and manipulate data. On page 436 of this issue, Yazdani and colleagues (Kitchen eta/.)1 show how a scanning tunnelling microscope can be used to assemble, atom by atom, a magnetic semiconductor. The result is an atomic-scale laboratory that allows an unprecedentedly clear picture of the electronic energies and magnetic interactions in the material concerned — manganese-doped gallium arsenide (refs 2, 3 and references therein). Crucially, the authors confirm predictions that the ferromagnetic interaction between pairs of magnetic atoms varies with their crystallographic orientation (their relative positions in the semiconductor lattice). That signals new ways to engineer, and possibly to enhance, the magnetic behaviour of ferromagnetic semiconductors — potentially with significant consequences for the burgeoning field of semiconductor spintronics.
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机译：灵巧的技术允许将磁性原子一个一个地放置在半导体晶体中。这是朝着一个宏伟目标迈出的又一步：可以同时存储和处理数据的计算机芯片。在本期杂志的第436页上，Yazdani及其同事（Kitchen eta ..）1展示了如何使用扫描隧道显微镜来逐个组装磁性半导体。结果是建立了原子级实验室，从而使有关材料-锰掺杂的砷化镓（参考文献2、3及其参考文献）中的电子能量和磁相互作用有了前所未有的清晰图像。至关重要的是，作者们证实了这样的预测：成对的磁性原子之间的铁磁相互作用会随其晶体学取向（它们在半导体晶格中的相对位置）而变化。这标志着设计和可能增强铁磁半导体磁性能的新方法-可能对半导体自旋电子学的迅速发展产生重大影响。
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