Marshall B. Frye

Advisor: Professor Lauren M. Garten

will defend a doctoral thesis entitled,

Engineering Polar Order and Switching via Interface and Defect Design in Emerging Ferroelectric Materials

On

Wednesday, April 1, 2026
3:00 pm - 5:00 pm

Price Gilbert 4222
Georgia Tech Library Dissertation Defense Room
or virtually via Zoom:
Zoom link

Committee
•    Prof. Lauren M. Garten – School of Materials Science and Engineering (advisor)
•    Prof. Juan-Pablo Correa-Baena – School of Materials Science and Engineering
•    Prof. Eric Vogel – School of Materials Science and Engineering
•    Prof. Antonio Facchetti – School of Materials Science and Engineering
•    Prof. Thomas Beechem – School of Mechanical Engineering, Purdue University

Abstract
As device thickness is reduced, interfaces and defects increasingly come to dominate over bulk properties. In ferroelectric materials, these effects have historically been detrimental, leading to critical thickness and performance limits that hinder commercial applications. This dissertation develops a unified framework in which interfaces and defects act as tunable parameters governing ferroelectric behavior, enabling the stabilization, modulation, and enhancement of ferroelectricity across diverse material systems. By combining innovative deposition strategies with advanced characterization, we develop scalable routes to synthesize two-dimensional (2D) ferroelectric chalcogenides and uncover interfacial mechanisms that stabilize and modulate polar order in complex oxide systems. Together, these results demonstrate how engineered interfacial structure and defect states can induce, control, and enhance ferroelectric behavior to enable next-generation logic, memory, and optoelectronic devices.
     In SnSe, we identify thickness-dependent structural transitions, polar stacking faults, and a tunable band gap. We then develop a mirror-rastering pulsed laser deposition (PLD) method for wafer-scale, continuous films. The highly energetic particles from PLD enable the stabilization of nonequilibrium polar stacking faults, which are confirmed by microscopy and spectroscopy methods. With these films, we demonstrate the first reported bulk ferroelectric measurements in SnSe, confirming ferroelectric switching.
     Extending the role of interfaces and defects to complex oxides, we reveal that an iron oxide interlayer stabilizes P63cm ScFeO3 (h-ScFeO3) on insulating substrates. Using this interlayer, we expand the device compatibility of h-ScFeO3 by stabilizing the phase on metal electrodes for the first time via interlayer epitaxy and show that strain relaxation from the interlayer surpasses limits in improper ferroelectrics, enabling polar distortion at the first layer.
     Finally, we show that defect states at an Al2O3–Hf0.5Zr0.5O2 interface enhance the coercive field by 3× and increase the memory window. Through phase-field modeling and polarization-dependent spectroscopy, a defect-dependent tunneling mechanism is discovered that governs ferroelectric switching in these nanoscale devices. Collectively, this work establishes interface and defect engineering as powerful, general tools for stabilizing ferroelectric phases and tuning functionality across diverse materials platforms.