Weakly-coupled quasi-1D helical modes in disordered 3D topological insulator quantum wires.
Weakly-coupled quasi-1D helical modes in disordered 3D topological insulator quantum wires.
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DOI：
10.1038/srep45276
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发表时间：
2017-04-04
影响因子：
4.6
通讯作者：
Giraud R
中科院分区：
文献类型：
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作者：
Dufouleur J;Veyrat L;Dassonneville B;Xypakis E;Bardarson JH;Nowka C;Hampel S;Schumann J;Eichler B;Schmidt OG;Büchner B;Giraud R
无序仍然是寻找凝聚态中拓扑超导电性的强健特征的关键限制因素。虽然干净的半导体量子线给出了从Majorana束缚态的角度讨论的有希望的结果，但无序使解释变得更加复杂。由于其完美的传输模式，3D拓扑绝缘体的量子线提供了一种重要的替代方案。需要考虑的一个重要方面是准一维表面模的混合，这是由于此类材料典型的强烈无序程度。在这里，我们揭示了这些模的能量展宽γ远远小于它们的能量间距Δ，这对于高度无序的介观纳米结构来说是一个不寻常的结果。高掺杂和无序的Bi2Se3和Bi2Te3纳米线的非普遍电导波动就证明了这一点。理论表明，这种独特的行为是具有强量子限制的自旋螺旋狄拉克费米子所特有的，由于其自旋结构，这些费米子在异常大的能量范围内保持了弹道性质。我们的结果证实了它们在研究拓扑超导电性方面的潜力，尽管它们具有很强的无序性。
Disorder remains a key limitation in the search for robust signatures of topological superconductivity in condensed matter. Whereas clean semiconducting quantum wires gave promising results discussed in terms of Majorana bound states, disorder makes the interpretation more complex. Quantum wires of 3D topological insulators offer a serious alternative due to their perfectly-transmitted mode. An important aspect to consider is the mixing of quasi-1D surface modes due to the strong degree of disorder typical for such materials. Here, we reveal that the energy broadening γ of such modes is much smaller than their energy spacing Δ, an unusual result for highly-disordered mesoscopic nanostructures. This is evidenced by non-universal conductance fluctuations in highly-doped and disordered Bi2Se3 and Bi2Te3 nanowires. Theory shows that such a unique behavior is specific to spin-helical Dirac fermions with strong quantum confinement, which retain ballistic properties over an unusually large energy scale due to their spin texture. Our result confirms their potential to investigate topological superconductivity without ambiguity despite strong disorder.