Imposing long-range ferromagnetic order in rare-earth-doped magnetic topological-insulator heterostructures
Imposing long-range ferromagnetic order in rare-earth-doped magnetic topological-insulator heterostructures
复制标题
DOI：
10.1103/physrevmaterials.2.054201
复制
发表时间：
2018-05
影响因子：
3.4
通讯作者：
L. Duffy;A. Frisk;D. M. Burn;N. Steinke;J. Herrero‐Martín;A. Ernst;G. Laan;T. Hesjedal
中科院分区：
文献类型：
--
作者：
L. Duffy;A. Frisk;D. M. Burn;N. Steinke;J. Herrero‐Martín;A. Ernst;G. Laan;T. Hesjedal
拓扑性质和磁序的结合可以导致新的量子态和奇异的物理现象，如量子反常霍尔（QAH）效应。拓扑表面状态中的磁隙的大小，QAH状态的鲁棒观测的关键，与掺杂的3D拓扑绝缘体（TI）的磁矩成比例。先驱过渡金属掺杂的（Sb，Bi）2（Se，Te）3薄膜只允许观察到高达约100 mK的QAH效应，尽管磁有序温度高得多。另一方面，高磁矩材料，如稀土掺杂的（Sb，Bi）2（Se，Te）3薄膜，显示出大的磁矩，但没有长程磁序。邻近耦合和界面效应，在人工异质结构中成倍增加，允许电子和磁性的工程。在这里，我们展示了高质量的Dy：Bi 2 Te 3/Cr：Sb 2 Te 3薄膜异质结的成功生长。使用X-射线磁谱，我们证明，高转变温度Cr：Sb 2 Te 3可以引入远程磁序在高磁矩Dy：Bi 2 Te 3-高达17 K的温度-与第一性原理计算，这揭示了起源的长程磁序在强反铁磁耦合之间的Dy和Cr磁矩在界面上延伸了几层。工程磁TI异质结构可能是一个理想的材料平台，观察QAH效应在液态氦温度及以上。
The combination of topological properties and magnetic order can lead to new quantum states and exotic physical phenomena, such as the quantum anomalous Hall (QAH) effect. The size of the magnetic gap in the topological surface states, key for the robust observation of the QAH state, scales with the magnetic moment of the doped 3D topological insulator (TI). The pioneering transition-metal doped (Sb,Bi)2(Se,Te)3 thin films only allow for the observation of the QAH effect up to some 100 mK, despite the much higher magnetic ordering temperatures. On the other hand, high magnetic moment materials, such as rare-earth doped (Sb,Bi)2(Se,Te)3 thin films, show large moments but no long-range magnetic order. Proximity coupling and interfacial effects, multiplied in artificial heterostructures, allow for the engineering of the electronic and magnetic properties. Here, we show the successful growth of high-quality Dy:Bi2Te3/Cr:Sb2Te3 thin film heterostructures. Using x-ray magnetic spectroscopy we demonstrate that high transition temperature Cr:Sb2Te3 can introduce long-range magnetic order in high-moment Dy:Bi2Te3 - up to a temperature of 17 K - in excellent agreement with first-principles calculations, which reveal the origin of the long-range magnetic order in a strong antiferromagnetic coupling between Dy and Cr magnetic moments at the interface extending over several layers. Engineered magnetic TI heterostructures may be an ideal materials platform for observing the QAH effect at liquid He temperatures and above.