The non-reciprocal electrical conductivity in a semiconducting \(p-n\) junction diode is a crucial, fundamental technological discovery that has helped the exponential development of computing power since the late twentieth century and has enabled today’s modern semiconducting devices that permeate our everyday life. The semiconductor industry has been able to roughly double the computing power of the integrated circuits every year by miniaturizing the semiconductor components as predicted by Gordon Moore in 1965 [1]. As these components reach their fundamental physical limit and Moore’s law comes to an end, there is the need to look for alternative platforms for solutions that can provide greater and more energy efficient computing power. Superconductivity, the physical state of solids with zero resistance, has been of great interest fundamentally and technologically since its discovery for its ability to transmit electrical currents with no Joule dissipation, which is the major source of energy loss in most electronic devices. It has already found some applications in the form of Josephson junctions, which are the most important circuit elements of a superconducting quantum bit [2], used in quantum computation. There has been a lot of interest over the years in the development of superconducting logic and memory [3]. The discovery of controlled non-reciprocal critical currents in a superconducting heterostructure in 2020, dubbed the ‘superconducting diode effect’ [4] renewed this interest and provided impetus along this new direction of research. Non-reciprocal conductivity in such systems offered by the unidirectional flow of supercurrents is analogous to a semiconductor diode and provides a natural platform for exploring applications in superconducting logic devices. Hence, it is of great interest to understand the underlying origin of this effect to be able to tune it precisely. A similar supercurrent diode effect was observed in a Josephson junction array made of InAs and aluminium [5], dubbed the ‘Josephson diode effect’. This thesis provides a brief and lucid overview to the field of superconductivity and non-reciprocal transport effects in solids that helps the reader better understand the context of the results and their significance before moving on to explore in detail the Josephson diode effect in two van der Waals materials with similar crystal structures 1T-NiTe2 and 1T-PtTe2. This chapter provides a short introduction to the Josephson diode effect and an overview of contents in the other chapters of this thesis, including the experimental results and the theoretical formalisms needed to understand the results.

Introduction and Scope of the Thesis

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发表日期：

2025年

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Pranava Keerthi Sivakumar

摘要

The non-reciprocal electrical conductivity in a semiconducting \(p-n\) junction diode is a crucial, fundamental technological discovery that has helped the exponential development of computing power since the late twentieth century and has enabled today’s modern semiconducting devices that permeate our everyday life. The semiconductor industry has been able to roughly double the computing power of the integrated circuits every year by miniaturizing the semiconductor components as predicted by Gordon Moore in 1965 [1]. As these components reach their fundamental physical limit and Moore’s law comes to an end, there is the need to look for alternative platforms for solutions that can provide greater and more energy efficient computing power. Superconductivity, the physical state of solids with zero resistance, has been of great interest fundamentally and technologically since its discovery for its ability to transmit electrical currents with no Joule dissipation, which is the major source of energy loss in most electronic devices. It has already found some applications in the form of Josephson junctions, which are the most important circuit elements of a superconducting quantum bit [2], used in quantum computation. There has been a lot of interest over the years in the development of superconducting logic and memory [3]. The discovery of controlled non-reciprocal critical currents in a superconducting heterostructure in 2020, dubbed the ‘superconducting diode effect’ [4] renewed this interest and provided impetus along this new direction of research. Non-reciprocal conductivity in such systems offered by the unidirectional flow of supercurrents is analogous to a semiconductor diode and provides a natural platform for exploring applications in superconducting logic devices. Hence, it is of great interest to understand the underlying origin of this effect to be able to tune it precisely. A similar supercurrent diode effect was observed in a Josephson junction array made of InAs and aluminium [5], dubbed the ‘Josephson diode effect’. This thesis provides a brief and lucid overview to the field of superconductivity and non-reciprocal transport effects in solids that helps the reader better understand the context of the results and their significance before moving on to explore in detail the Josephson diode effect in two van der Waals materials with similar crystal structures 1T-NiTe2 and 1T-PtTe2. This chapter provides a short introduction to the Josephson diode effect and an overview of contents in the other chapters of this thesis, including the experimental results and the theoretical formalisms needed to understand the results.