Skip to main content

MSE Department Seminar

Quantized dislocations for dislocated functional and quantum materials

A dislocation, just like a phonon, is a type of atomic lattice displacement but subject to an extra topological constraint. However, unlike the phonon which has been quantized for decades, the dislocation has long remained classical. This presentation is a pedagogical introduction on our recent theoretical effort of quantized dislocation, aka the "dislon" theory, with a focus on new phenomena and predictive power.

Uncovering Strain, Dislocations, and Ripples In Two-Dimensional Lateral Heterojunctions by Transmission Electron Microscopy

Two-dimensional (2D) layered crystals are a promising class of materials for post silicon electronics. Due to their atomic thinness, flexibility, and versatile electrical properties (i.e. conductors, semiconductors, and insulators), we can envision future ultra-small, flexible computers completely comprised of various 2D materials. For this application, lateral heterostructures of 2D materials play a major role, as they are the fundamental elements in a circuit, such as p-n junctions and metal-semiconductor contacts.

Impact of Point Defects on Efficiency of Devices

Point defects may act as compensating centers, charge traps, or radiative or nonradiative recombination centers. In addition, unintentional impurities often play an equally detrimental role; for instance, carbon that is unavoidably incorporated during growth can act as a recombination center in nitrides, or as a charge trap in oxide dielectrics.  Theoretical advances now enable us to calculate the electronic and optical properties as well as radiative and nonradiative carrier capture coefficients with unprecedented accuracy.

Probing α-synuclein amyloid formation by Raman microspectroscopy

Parkinson's disease (PD) is a prevalent age-related neurodegenerative disease associated with the aggregation of the neuronal protein α-synuclein (α-syn) into β-sheet-rich fibrils, called amyloid. Natively, α-syn is an intrinsically disordered protein, and it is thought conformational changes in α-syn are linked to its pathogenicity. Thus, the ability to determine conformational changes of α-syn from soluble, unstructured monomers to β-sheet-rich aggregates is critical for understanding the role of amyloid fibrils in disease progression.

User-Programmable Hydrogel Biomaterials to Probe and Direct 4D Stem Cell Fate

The extracellular matrix directs stem cell function through a complex choreography of biomacromolecular interactions in a tissue-dependent manner. Far from static, this hierarchical milieu of biochemical and biophysical cues presented within the native cellular niche is both spatially complex and ever changing.

The Striking Geometries of Self-assembled Hierarchical Structures

In nature, soft structures, such as protein assemblies, can organize reversibly into functional and often hierarchical architectures through noncovalent interactions. Encoding this dynamic capability in synthetic materials has remained an elusive goal. Through examples ranging from colloidal to molecular self-assembly I will illustrate the remarkable structures that have been realized experimentally in recent years.