论文标题
在高-TC铜板超导体上生长的拓扑绝缘体中的库仑封锁作用
Coulomb Blockade Effects in a Topological Insulator Grown on a High-Tc Cuprate Superconductor
论文作者
论文摘要
在拓扑绝缘子和高-TC蛋糕的异质结构中邻近诱导的超导性的证据一直存在激烈的争论。我们使用分子束外延在铜材料BI2SR2CACU2O8+X上生长拓扑绝缘子BI2TE3的薄膜，并使用低温扫描隧道显微镜和光谱学研究BI2TE3的表面。在少数单元厚的BI2TE3膜中，我们在DI/DV光谱中的Fermi Energy中发现了V形间隙样曲线。通过减少BI2TE3薄膜的覆盖范围以创建纳米级岛，我们发现这种光谱在巨大的硬化上变成了更大的硬间隙，可以理解为库仑封锁缝隙。 DI/DV光谱与BI2TE3岛的横向大小以及地形测量结果的演变得到了支持，该谱图显示了将BI2TE3和BI2SR2CACU2O8+X隔开的额外屏障。我们得出的结论是，BI2TE3膜中DI/DV光谱中的显着差距样特征不是接近诱导的超导间隙。取而代之的是，可以通过库仑封锁效应来解释，该效应考虑到界面处的其他电阻和电容耦合。我们的实验为具有埋入界面的复杂异质结构的隧道测量提供了新的见解。
The evidence for proximity-induced superconductivity in heterostructures of topological insulators and high-Tc cuprates has been intensely debated. We use molecular beam epitaxy to grow thin films of topological insulator Bi2Te3 on a cuprate Bi2Sr2CaCu2O8+x, and study the surface of Bi2Te3 using low-temperature scanning tunneling microscopy and spectroscopy. In few unit-cell thick Bi2Te3 films, we find a V-shaped gap-like feature at the Fermi energy in dI/dV spectra. By reducing the coverage of Bi2Te3 films to create nanoscale islands, we discover that this spectral feature dramatically evolves into a much larger hard gap, which can be understood as a Coulomb blockade gap. This conclusion is supported by the evolution of dI/dV spectra with the lateral size of Bi2Te3 islands, as well as by topographic measurements that show an additional barrier separating Bi2Te3 and Bi2Sr2CaCu2O8+x. We conclude that the prominent gap-like feature in dI/dV spectra in Bi2Te3 films is not a proximity-induced superconducting gap. Instead, it can be explained by Coulomb blockade effects, which take into account additional resistive and capacitive coupling at the interface. Our experiments provide a fresh insight into the tunneling measurements of complex heterostructures with buried interfaces.
