Parallel and series conduction model in Topological Insulators

TL;DR

This paper investigates the temperature-dependent resistance in topological insulators using parallel and series resistor models to understand the coupling between bulk and surface states.

Contribution

It introduces a resistor model framework to analyze the R-T behavior of topological insulators, capturing the effects of bulk-surface coupling or decoupling.

Findings

Series model describes decoupled bulk and surface states.

Parallel model captures coupled bulk and surface conduction.

Resistor models effectively explain experimental R-T behaviors.

Abstract

In the past few years there has been a surge in the material science engineering in order to synthesize bulk insulating and surface metallic Topological Insulating (TI) materials. This quest is not only theoretically important but also promising from the novel application perspective. The dependence of temperature on resistance (R-T) of a particular sample reveals a plethora of information about the electronic properties especially in a unique sample like TI where there are two components comprising of an insulating bulk and metallic surface states. Depending on the amount of intrinsic doping during the sample formation, the bulk can either couple or remain decoupled with the surface. The former leads to a metallic R-T profile whereas the latter is captured by an insulating R-T behavior. These two behaviors can be represented by series and parallel resistor models respectively. In this work we study the R-T behavior in the framework of resistor models capturing the essential features of our sample.