First principles characterization of the chiroptical and magnetoelectric properties of chiral crystals
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Authors
Multunas, Christian
Issue Date
2024-08
Type
Electronic thesis
Thesis
Thesis
Language
en_US
Keywords
Physics
Alternative Title
Abstract
Research from the past two decades into chiral crystals has uncovered a variety of novel and impressive optical and magnetoelectric transport properties, prompting a push for first principles theorization to aid in materials discovery for potential applications in spintronic logic devices. Herein we provide a theoretical framework for the prediction of circular dichroism (CD) in crystals, demonstrating how the optical response is highly directionally dependent in complex perovskites. We further decompose the CD using orbital projections to show how the inorganic versus organic pieces of a perovskite affect its chiroptical properties. We next use first principles methods to quantify the internal magnetic field in arbitrary crystals, classifying the spin-orbit coupling (SOC) by its Rashba, Dresselhaus, and Weyl character. We demonstrate how chirality can be induced in achiral materials through the application of mechanical strain, and how the resulting SOC displays Weyl-like behavior. We follow this by assessing the use of inversion symmetry-breaking as a means of cryogenic cooling. Through the application of an external electric field, we quantify the entropy increase due to induced Rashba splitting in zincblende III-V semiconductors. We will show how sub-1K cooling is feasible through the use of electrically-tunable spin-orbit materials, providing an alternative to standard cryogenic cooling methods which require rare materials. Finally, we develop a theoretical framework for the computation of bilinear magnetoresistance in Rashba-split semiconductors. We show how the angular displacement between the electric and magnetic fields leads to minimized and maximized currents in wurtzite III-V systems. Our findings provide us with further opportunities to elucidate the rich physics arising from the lack of inversion symmetry.
Description
August 2024
School of Science
School of Science
Full Citation
Publisher
Rensselaer Polytechnic Institute, Troy, NY