Demonstration of surface transport in a hybrid Bi2Se3/Bi2Te3 heterostructure

TL;DR

This study demonstrates that a single quintuple layer of Bi2Se3 on Bi2Te3 heterostructure exhibits surface transport properties similar to pure Bi2Se3, highlighting the dominant role of the Bi2Se3 layer.

Contribution

It provides systematic experimental evidence of surface transport in a Bi2Se3/Bi2Te3 heterostructure, a previously unexplored area in topological insulator research.

Findings

Surface state of heterostructure resembles Bi2Se3

Transport properties dominated by Bi2Se3 layer

Linear magnetoresistance similar to Bi2Se3

Abstract

In spite of much work on topological insulators (TIs), systematic experiments for TI/TI heterostructures remain absent. We grow a high quality heterostructure containing single quintuple layer (QL) of Bi2Se3 on 19 QLs of Bi2Te3 and compare its transport properties with 20 QLs Bi2Se3 and 20 QLs Bi2Te3. All three films are grown on insulating sapphire (0001) substrates by molecular beam epitaxy (MBE). In situ angle-resolved photoemission spectroscopy (ARPES) provides direct evidence that the surface state of 1 QL Bi2Se3 / 19 QLs Bi2Te3 heterostructure is similar to the surface state of the 20 QLs Bi2Se3 and different with that of the 20 QLs Bi2Te3. In ex situ transport measurements, the observed linear magnetoresistance (MR) and weak antilocalization (WAL) of the hybrid heterostructure are similar to that of the pure Bi2Se3 film and not the Bi2Te3 film. This suggests that the single Bi2Se3 QL layer on top of 19 QLs Bi2Te3 dominates its transport properties.