Dual nature of magnetic dopants and competing trends in topological insulators.
Dual nature of magnetic dopants and competing trends in topological insulators.
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DOI：
10.1038/ncomms12027
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发表时间：
2016-06-27
影响因子：
16.6
通讯作者：
Balatsky AV
中科院分区：
文献类型：
--
作者：
Sessi P;Biswas RR;Bathon T;Storz O;Wilfert S;Barla A;Kokh KA;Tereshchenko OE;Fauth K;Bode M;Balatsky AV
据报道，与磁性杂质相互作用的拓扑绝缘体具有几种非常规效应。由于时间反转对称性的破坏，这些现象被描述在狄拉克准粒子缝隙的框架内。然而，绝大多数研究表明，即使拓扑绝缘体变得有磁性，狄拉克点附近也存在有限密度的态。在这里，我们在原子尺度上映射拓扑态对磁性杂质的响应。我们证明了磁有序和无间隙态可以共存。我们展示了这是如何在两个相反的趋势之间微妙平衡的结果，即缺口打开和狄拉克节点杂质带的出现，两者都是由磁性掺杂引起的。我们的结果证明了一种比曾经普遍假设的更复杂和更丰富的情景，展示了在这类迷人的材料中如何产生和控制不同的电子和磁态。磁性杂质破坏了拓扑绝缘子的时间反转对称性，但理论和实验一直存在分歧。在这里，作者在原子水平上研究了拓扑态对磁性掺杂的响应，并表明，与通常认为的相反，磁有序和无间隙态可以共存。
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. Magnetic impurities break time reversal symmetry in topological insulators, but there has been disagreement between theory and experiment. Here, the authors study the response of topological states to magnetic dopants at the atomic level and show that, contrary to what generally believed, magnetic order and gapless states can coexist.