Physikalisches Institut, Experimentelle Physik II, Universität Würzburg, Am Hubland, 97074 Würzburg, Germany.
Department of Physics and Astronomy, Purdue University, 525 Northwestern Avenue, West Lafayette, Indiana 47907, USA.
Nat Commun. 2016 Jun 27;7:12027. doi: 10.1038/ncomms12027.
Topological insulators interacting with magnetic impurities have been reported to host several unconventional effects. These phenomena are described within the framework of gapping Dirac quasiparticles due to broken time-reversal symmetry. However, the overwhelming majority of studies demonstrate the presence of a finite density of states near the Dirac point even once topological insulators become magnetic. Here, we map the response of topological states to magnetic impurities at the atomic scale. We demonstrate that magnetic order and gapless states can coexist. We show how this is the result of the delicate balance between two opposite trends, that is, gap opening and emergence of a Dirac node impurity band, both induced by the magnetic dopants. Our results evidence a more intricate and rich scenario with respect to the once generally assumed, showing how different electronic and magnetic states may be generated and controlled in this fascinating class of materials.
拓扑绝缘体与磁性杂质相互作用被报道具有多种非常规效应。这些现象是在由于时间反演对称性破缺而产生的狄拉克准粒子隙的框架内描述的。然而，绝大多数研究表明，即使拓扑绝缘体成为磁性的，在狄拉克点附近仍然存在有限的态密度。在这里，我们在原子尺度上绘制了拓扑态对磁性杂质的响应。我们证明了磁有序和无带隙状态可以共存。我们展示了这是如何由于两种相反趋势之间的微妙平衡而产生的，即由磁性掺杂剂引起的带隙打开和狄拉克节杂质带的出现。我们的结果相对于曾经普遍假设的情况提供了一个更复杂和丰富的场景，展示了如何在这一迷人的材料类别中产生和控制不同的电子和磁性状态。
