Optional ZOOM LINK
Meeting ID: 929 0143 2317
Passcode: 189191

"First-principles studies of electric polarization effects in defects, ferroelectrics and antiferroelectrics"

Abstract

Density functional theory (DFT) has been at the forefront of computational material science for a few decades, revolutionizing our understanding of the interplay between the chemical and physical properties of materials. In this thesis proposal, I will discuss how DFT can be used to study electric polarization effects in solids with a focus on point defects, ferroelectric and antiferroelectric materials.

Point defects have become central for quantum information science applications due to their ability to act as single-photon emitters with a spin degree of freedom. Spectral diffusion, the broadening of the optical emission line, can significantly impact the performance of defect-based quantum networks. The coupling between the dipole moment change upon electronic transition and stray electric fields in the vicinity of the defect, an effect known as Stark shift, is considered to be one of the main sources of spectral diffusion. In the first part of this proposal, I will present a methodology we recently developed to calculate the Stark shift of point defects using DFT calculations with a focus on the nitrogen-vacancy center in diamond.

Materials with an electrically switchable spontaneous polarization, ie ferroelectrics, are highly attractive for many electronic-based applications. Most of the known ferroelectrics are based on the perovskite structure which has intrinsic limitations related to their compatibility with the current CMOS technology or the disappearance of ferroelectricity in ultra-thin films. In this context, discovering new ferroelectrics overcoming these challenges could be greatly beneficial. The second part of this thesis proposal will be dedicated to the discovery of new ferroelectrics starting from phonon databases. Finally, in the last part of this proposal, I will discuss how antiferroelectrics, materials with a polar phase close in energy to the non-polar ground-state, can be used to obtain ultra-high electromechanical responses in thin-films.

Thesis Committee

• Geoffroy Hautier (chair)
• William Scheideler
• Mattias Fitzpatrick
• Philippe Ghosez (ULiège)

Contact

For more information, contact Thayer Registrar at thayer.registrar@dartmouth.edu.