Device Research Laboratory, Department of Electrical Engineering, University of California , Los Angeles, California 90095, United States.
Nano Lett. 2013 Oct 9;13(10):4587-93. doi: 10.1021/nl4020638. Epub 2013 Sep 12.
A new class of devices based on topological insulators (TI) can be achieved by the direct engineering of the time-reversal-symmetry (TRS) protected surface states. In the meantime, a variety of interesting phenomena are also expected when additional ferromagnetism is introduced to the original topological order. In this Letter, we report the magnetic responses from the magnetically modulation-doped (Bi(z)Sb(1-z))2Te3/Cr(x)(Bi(y)Sb(1-y))2Te3 bilayer films. By electrically tuning the Fermi level across the Dirac point, we show that the top TI surface carriers can effectively mediate the magnetic impurities and generate robust ferromagnetic order. More importantly, such surface magneto-electric effects can be either enhanced or suppressed, depending on the magnetic interaction range inside the TI heterostructures. The manipulation of surface-related ferromagnetism realized in our modulation-doped TI device is important for the realization of TRS-breaking topological physics, and it may also lead to new applications of TI-based multifunctional heterostructures.
一类新的基于拓扑绝缘体 (TI) 的器件可以通过对时间反演对称 (TRS) 保护的表面态进行直接工程设计来实现。同时，当在原始拓扑序中引入额外的铁磁体时，预计会出现各种有趣的现象。在这封信中，我们报告了磁调制掺杂 (Bi(z)Sb(1-z))2Te3/Cr(x)(Bi(y)Sb(1-y))2Te3 双层薄膜的磁响应。通过电调谐费米能级越过狄拉克点，我们表明顶部 TI 表面载流子可以有效地介导磁杂质并产生稳定的铁磁有序。更重要的是，这种表面磁电效应可以增强或抑制，具体取决于 TI 异质结构内部的磁相互作用范围。我们在调制掺杂 TI 器件中实现的表面相关铁磁体的操控对于实现 TRS 破坏拓扑物理非常重要，并且可能会导致基于 TI 的多功能异质结构的新应用。
