Year

2021

Degree Name

Doctor of Philosophy

Department

Institute for Superconducting and Electronic Materials

Abstract

The demand for more efficient and smaller sized electronic devices with increased functionality has driven the semiconductor industry for decades. Most of the information processing and electrical circuitry has been based on the complementary metal oxide semiconductor (CMOS) devices until the recent years. The miniaturization of these devices, however, has reached its functional limit and newer ways are required to keep up with the increasing demands, computing becoming vastly used and even more relevant with the changing world. To overcome this problem, many approaches have been taken to upgrade the present electronic and computing devices including multi-core processing and the incorporation of new materials. This manoeuvre towards the modern digital logic technologies beyond CMOS has been striving for the technological advancement in the modern electronics.

Topological materials are the quantum materials with linear electronic distributions and protected edge/surfaces states where electrons can move without back scattering. Therefore, zero or low energy loss and high speed electronic devices can be fabricated by using topological materials. This makes them a perfect choice for use in modern, beyond CMOS, electronics and computing. Topological insulators with insulating bulks and conducting surfaces and topological semimetals with conducting bulks and uniquely conducting surface states have been extensively investigated for their exotic transport properties like quantum anomalous hall effect, chiral anomaly, high magnetoresistance, ultra-high mobility and super-fast on/off switching rates.

This dissertation explores the magnetic and electrical transport properties of topological semimetals/insulators characterized by Chern invariant that can be applied in the modern computing and topological electronics. Topological materials MoSi2, Mn3Sn, Mn3Ge and MnBi2Te4 are the prime focus of this study. The approach of comparison of these properties in bulk single and poly- crystalline and thin film form is applied to investigate the differences between the bulk and Pulsed Laser Deposited (PLD) thin films. The effects of substrates on the growth and transport properties of these films, the response in externally applied magnetic field at different temperatures and the variation of magnetization with the applied fields at various temperatures are also addressed and analysed.

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Unless otherwise indicated, the views expressed in this thesis are those of the author and do not necessarily represent the views of the University of Wollongong.