MSE Department Seminar

An ability to first visualize and then shape the nanoworld is of great scientific and technological interest. In this talk, we present two unusual approaches that both allow the formation of structures with atomic precision. In the first approach, we are capitalizing on the fact that with the continued development of scanning probe microscopy techniques, atomic structure imaging and manipulation of single molecules has become possible, providing unprecedented insight into chemistry at the single-molecule level.

Organic inorganic hybrid semiconductors exhibit a rich interplay between organic and inorganic components, resulting in unique tunable electronic, optical, and structural properties. Central to their functionality is the control of dynamic structural phenomena, such as phase transitions, lattice distortions, and structural reorganization, which are influenced by external stimuli like temperature, light, or electric fields. I will present strategies to manipulate these dynamic structures, including compositional tuning, external field application, and molecular design.

Interfaces of two dimensional (2D) van der Waals (vdW) crystals constitute the most versatile material platforms for the exploration of new physical phenomena, particularly emergent quantum phases. Here we apply femtosecond pump-probe spectroscopy/microscopy to develop a time-domain view of quantum phases at 2D vdW interfaces of semiconducting, ferro/antiferro-magnetic, and ferroelectric materials. For transitional metal dichalcogenide (TMDC) moiré interfaces, we show the robustness of correlated electron phases and their coupling to phonons.

Multi-dimensional Coherent Terahertz Spectroscopy (THz-MDCS) is a new tool for studying with unprecedented resolution and for controlling quantum materials, by using a pair of phase-locked, intense Terahertz (THz) laser pulses. Establishing this experimental technique in superconductors and topological materials requires solving a non-equilibrium many-body problem that spans across several fields of current interest, including light-induced superconductivity, parametric driving of metastable phases, and quantum entanglement of supercurrent qubits.

In this talk, I will discuss several symmetries in quantum physics that have recently led to the observations of intriguing optical phenomena and the realizations of novel photonic functionalities. Different from canonical quantum mechanics, these symmetries imply non-Hermiticity that is difficult to realize in high-energy physics or condensed matter systems in a controlled fashion.

Fast ion conducting glasses have long been considered as alternatives to flammable liquid electrolytes in Li batteries. However, to date, there has never been before the unique combination of required electrochemical properties in any one such glass for its use as a solid electrolyte with the equally important requirements of viscoelastic behavior to form them into thin films suitable for high ion conductivity separators.

Following molecular-level chirality studies, the chirality of nanomaterials is a newly emerging focal point in the field, catalyzed by the discovery of intense polarization rotation in individual nanoparticles (NPs) and their assemblies.

Lithium-based batteries are essential in modern energy supply systems. There is a demand for safer and higher energy density batteries, and for securing the supply chain of Li for production of these batteries. In this talk, I will cover experimental and modeling studies that focus on the interactions among ions, solvents, and polymers in both battery and separation systems, and how these interactions can be optimized through molecular-scale design.

This year marks the 27th anniversary of IBM’s CMOS/Cu BEOL [Back End of the (manufacturing) Line] on-chip interconnect technology reaching production, with the first high-end Cu CPU chips passing manufacturing qualification and being sampled to customers. This announcement shocked the industry, who were unaware that Cu had been taken beyond the early research phase.

Innovative materials are needed to tackle current major challenges in energy storage and generation. However, the design of new materials largely relies on experimental trial and error, limiting the number explored compounds relative to the entire space of possible compounds. In this presentation, I will discuss our approach to materials design, which integrates machine learning (ML) techniques with quantum mechanics-based computations.