补偿拓扑绝缘体中电子和空穴的水坑

Charge puddles in a completely compensated topological insulator

Compensation of intrinsic charges is widely used to reduce the bulk conductivity of 3D topological insulators (TIs). Here we use low temperature electron irradiation-induced defects paired with in-situ electrical transport measurements to fine-tune the degree of compensation in Bi2Te3. The coexistence of electrons and holes at the point of optimal compensation can only be explained by bulk carriers forming charge puddles. These need to be considered to understand the electric transport in compensated TI samples, irrespective of the method of compensation.

Large positive magneto-conductivity at microwave frequencies in the compensated topological insulator BiSbTeSe2

The bulk electronic properties of compensated topological insulators are strongly affected by the self-organized formation of charge puddles at low temperature, but their response in the microwave frequency range is little studied. We employed broadband impedance spectroscopy up to 5 GHz to address the ac transport properties of well-compensated BiSbTeSe2, where charge puddles are known to form as metallic entities embedded in an insulating host. It turns out that the average puddle size sets the characteristic frequency cut-off in the GHz range, across which the insulating dc behavior is sepa…

Charge puddles in the bulk and on the surface of the topological insulator BiSbTeSe$_2$ studied by scanning tunneling microscopy and optical spectroscopy

The topological insulator BiSbTeSe$_2$ corresponds to a compensated semiconductor in which strong Coulomb disorder gives rise to the formation of charge puddles, i.e., local accumulations of charge carriers, both in the bulk and on the surface. Bulk puddles are formed if the fluctuations of the Coulomb potential are as large as half of the band gap. The gapless surface, in contrast, is sensitive to small fluctuations but the potential is strongly suppressed due to the additional screening channel provided by metallic surface carriers. To study the quantitative relationship between the properti…

补偿型拓扑磁体 MnBi$_{2-x}$Sb$_x$Te$_4$ 中反位缺陷诱导的无序

Anti-site defect-induced disorder in compensated topological magnet MnBi$_{2-x}$Sb$_x$Te$_4$

本研究利用 STM/S 对 $x=0.64$ 的 MBST 进行统计分析，发现 (Bi,Sb)$_{\ m Mn}$ 反位缺陷主导掺杂涨落、形成电荷坑并闭合输运能隙。

非常规$p$-波磁体的最小模型与输运性质

Minimal Models and Transport Properties of Unconventional $p$-Wave Magnets

本研究针对受复合时间反演平移对称性保护的新型非常规$p$-波补偿磁体，构建了基于最小紧束缚模型的有效解析模型，揭示其无净磁化下的大磁阻等输运特性，拓宽了自旋电子学器件的材料选择。

表征拓扑绝缘体 (Bi$_{1-x}$Sb$_x$)$_2$Te$_3$ 薄膜中的化学势无序

Characterizing the chemical potential disorder in the topological insulator (Bi$_{1-x}$Sb$_x$)$_2$Te$_3$ thin films

利用扫描隧道显微镜和能谱学研究拓扑绝缘体薄膜的化学势无序，发现电势涨落与 Landau level 展宽正相关，并确定 $x\approx 0.65$ 可实现较低涨落和理想 Dirac point 位置。