Behner Gerrit, Jalil Abdur Rehman, Heffels Dennis, Kölzer Jonas, Moors Kristof, Mertens Jonas, Zimmermann Erik, Mussler Gregor, Schüffelgen Peter, Lüth Hans, Grützmacher Detlev, Schäpers Thomas
Peter Grünberg Institut (PGI-9), Forschungszentrum Jülich, 52425 Jülich, Germany.
JARA-Fundamentals of Future Information Technology, Jülich-Aachen Research Alliance, Forschungszentrum Jülich and RWTH Aachen University, 52425 Jülich, Germany.
Nano Lett. 2023 Jul 26;23(14):6347-6353. doi: 10.1021/acs.nanolett.3c00905. Epub 2023 Jul 3.
We present low-temperature magnetotransport measurements on selectively grown SbTe-based topological insulator ring structures. These devices display clear Aharonov-Bohm oscillations in the conductance originating from phase-coherent transport around the ring. The temperature dependence of the oscillation amplitude indicates that the Aharonov-Bohm oscillations originate from ballistic transport along the ring arms. We attribute these oscillations to the topological surface states. Further insight into the phase coherence is gained by comparing with similar Aharonov-Bohm-type oscillations in topological insulator nanoribbons exposed to an axial magnetic field. Here, quasi-ballistic phase-coherent transport is confirmed for closed-loop topological surface states in the transverse direction enclosing the nanoribbon. In contrast, the appearance of universal conductance fluctuations indicates phase-coherent transport in the diffusive regime, which is attributed to bulk carrier transport. Thus, it appears that even in the presence of diffusive -type charge carriers in Aharonov-Bohm ring structures, phase-coherent quasi-ballistic transport of topological surface states is maintained over long distances.
我们展示了对选择性生长的基于SbTe的拓扑绝缘体环形结构进行的低温磁输运测量。这些器件在电导中显示出清晰的阿哈罗诺夫-玻姆振荡，其源于围绕环的相位相干输运。振荡幅度的温度依赖性表明，阿哈罗诺夫-玻姆振荡源于沿环臂的弹道输运。我们将这些振荡归因于拓扑表面态。通过与暴露于轴向磁场的拓扑绝缘体纳米带中类似的阿哈罗诺夫-玻姆型振荡进行比较，对相位相干有了进一步的了解。在这里，对于围绕纳米带的横向闭环拓扑表面态，确认了准弹道相位相干输运。相比之下，普遍电导涨落的出现表明在扩散区域存在相位相干输运，这归因于体载流子输运。因此，即使在阿哈罗诺夫-玻姆环形结构中存在扩散型电荷载流子的情况下，拓扑表面态的相位相干准弹道输运似乎仍能在长距离上得以维持。
