Date of Graduation

8-2024

Document Type

Dissertation

Degree Name

Doctor of Philosophy in Materials Science & Engineering (PhD)

Degree Level

Graduate

Department

Materials Science & Engineering

Advisor/Mentor

Manasreh, Bothina H.

Committee Member

Bellaiche, Laurent

Second Committee Member

Manasreh, Omar O.

Third Committee Member

Ware, Morgan E.

Fourth Committee Member

Leftwich, Matthew B.

Keywords

Materials design; Computational alchemy; Heusler alloys

Abstract

Intelligent materials discovery and design plays a pivotal role in advancement of spintronics, optoelectronics and thermoelectric devices and technology. In this study, we investigate three types of materials using first principles calculations. First, the structural, electronic, and magnetic properties of CrTiCoZ (Z = Al, Si) equiatomic quaternary Heusler alloys were investigated. CrTiCoAl compound was found to exhibit a half metallic ferromagnetic structure and Curie temperature above room temperature, which makes it an ideal candidate for magnetic tunnel junction, the basic building block of Spintronic devices. Second, we use Green’s function to obtain the finite temperature phonons by including quartic anharmonicity as well as lattice thermal conductivity. Negative thermal expansion and low lattice thermal conductivity was predicted for InS monolayer upon the inclusion of quartic anharmonicity, which indicates its application for thermoelectric generators. The third investigated structure was As2S3 monolayer, which possesses an anisotropic behavior that makes it promising for optoelectronic performance. The strain engineering on As2X3 (X = S, Te) monolayers indicated a transition from indirect to direct bandgap for a uniaxial tensile strain of +8% along b-axis which makes it suitable for photodetector applications.

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