Award Date

December 2023

Degree Type

Thesis

Degree Name

Master of Science (MS)

Department

Physics and Astronomy

First Committee Member

Joshua Island

Second Committee Member

David Shelton

Third Committee Member

Yan Zhou

Fourth Committee Member

Keith V. Lawler

Fifth Committee Member

Boo Shan Tseng

Number of Pages

98

Abstract

Josephson junctions have garnered significant attention due to their unique electronic properties and applications in quantum devices. In this thesis, we investigate the fabrication processes and characterization of two-dimensional (2D) Josephson junctions consisting of layered van der Waals materials: niobium diselenide (2H-NbSe2) and few layered tungsten ditelluride (1T’-WTe2). The reduction of dimensionality can bring forth unique characteristics in certain materials that are not seen in their bulk counterparts, making them prime candidates for physical exploration. 2H-NbSe2 is an s-wave superconductor at temperatures near and below 7 K. 1T’-WTe2 is a semimetal in bulk but is an intrinsic quantum spin Hall insulator in monolayer form, with a large (55 meV) band gap. Both materials exhibit exotic behavior, and the coupling of the two provides the necessary environment for entangled quasiparticles known as Majorana zero modes (MZMs). In a topologically protected environment, MZMs could be used to encode quantum information, addressing one of the leading obstacles of decoherence in current solid-state qubits. In our investigation of Josephson junctions with 2H-NbSe2 and few layer 1T’-WTe2, disorder became a prevalent issue, hindering expected electronic transport properties of the Josephson effect. The devices studied in this thesis exhibit transparent and non-transparent Andreev reflections. This comparison sheds light on the distinct behaviors of highly disordered and low-disordered interfaces and their implications for quantum effects.

Keywords

Andreev reflection; Josephson junction; proximity effect; quantum effects; transport; two-dimensional

Disciplines

Condensed Matter Physics | Nanoscience and Nanotechnology

Degree Grantor

University of Nevada, Las Vegas

Language

English

Rights

IN COPYRIGHT. For more information about this rights statement, please visit http://rightsstatements.org/vocab/InC/1.0/

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