论文标题
设计师拓扑绝缘子具有增强的间隙和抑制bi2SE3/SB2TE3超短期期超晶格的散装传导
Designer topological insulator with enhanced gap and suppressed bulk conduction in Bi2Se3/Sb2Te3 ultra-short period superlattices
论文作者
论文摘要
提出了一种新的方法，通过使用两个交替拓扑绝缘体层的短期超晶格（SL）来减少大量电导。从观察到的散装背景掺杂量减少一个数量级，从1.2x1020 cm-3到8.5x1018 cm-3，随着BI2SE3/SB2TE3 SLS的周期分别降低到12 nm到5 nm，获得了超晶格差距增强（SGE）的证据。紧密的结合计算表明，在非常薄的时期制度中，可以通过适当的材料选择来实现重要的SGE。交替的BI2SE3和SB2TE3层的超薄SL表现为一种新的设计师材料，其散装带隙比具有最大带隙的组成层的带隙大60％，同时保留了拓扑表面特征。在非常薄的SL样品的低温磁电导率中明显的弱抗钙化（WAL）尖缘的分析证实，SL结构的顶部和底部表面以Dirac表面状态表现。这种方法代表了一个有希望的且尚未被探索的平台，用于构建真正绝缘的散装TI。
A novel approach to reduce bulk conductance by the use of short period superlattices (SL) of two alternating topological insulator layers is presented. Evidence for a superlattice gap enhancement (SGE) was obtained from the observed reduction of bulk background doping by more than one order of magnitude, from 1.2x1020 cm-3 to 8.5x1018 cm-3 as the period of Bi2Se3/Sb2Te3 SLs is decreased from 12 nm to 5 nm, respectively. Tight binding calculations show that in the very thin period regime, a significant SGE can be achieved by the appropriate choice of materials. The ultrathin SL of alternating Bi2Se3 and Sb2Te3 layers behaves as a new designer material with a bulk bandgap as much as 60% larger than the bandgap of the constituent layer with the largest bandgap, while retaining topological surface features. Analysis of the weak antilocalization (WAL) cusp evident in the low temperature magneto-conductance of a very thin period SL sample grown confirms that the top and bottom surfaces of the SL structure behave as Dirac surface states. This approach represents a promising and yet to be explored platform for building truly insulating bulk TIs.
