Increased Phase Coherence Length in a Porous Topological Insulator

TL;DR

Introducing nanoscale porosity in Bi2Te3 thin films enhances the phase coherence length of topological surface states, potentially improving their application in low energy electronics and spintronics.

Contribution

This study demonstrates that nanoporosity increases phase coherence length without destroying topological surface states in Bi2Te3 thin films.

Findings

Phase coherence length doubled in porous samples

Porosity increased surface-like transport behavior

Topological surface states remain intact and are enhanced

Abstract

The surface area of Bi2Te3 thin films was increased by introducing nanoscale porosity. Temperature dependent resistivity and magnetotransport measurements were conducted both on as-grown and porous samples (23 and 70 nm). The longitudinal resistivity of the porous samples became more metallic, indicating the increased surface area resulted in transport that was more surface-like. Weak antilocalization (WAL) was present in all samples, and remarkably the phase coherence length doubled in the porous samples. This increase is likely due to the large Fermi velocity of the Dirac surface states. Our results show that the introduction of nanoporosity does not destroy the topological surface states but rather enhances them, making these nanostructured materials promising for low energy electronics, spintronics and thermoelectrics.