Signatures of topology in ballistic bulk transport of HgTequantum wells

摘要

We calculate transport properties of HgTe quantum wells that exhibit the quantum spin Hall effect. We con-centrate on the ballistic bulk contribution as a function of aspect ratio and Fermi energy. We show that the conductance and the shot noise are distinctively different for the so-called normal regime (the topologically triv-ial case) and the so-called inverted regime (the topologically non-trivial case). Thus, it is possible to verify the topological order of two-dimensional topological insulators such as HgTe quantum wells not only via observable edge properties but also via observable bulk properties. In addition, we show that the bulk contribution can even exceed the edge contribution for certain parameter regimes (and in all regimes for the case of the shot noise). We test the validity of our analytical approach against a tight-binding model that allows us to include random disorder numerically which is shown to have only a minor effect as long as its strength does not exceed the bulk gap.