Spring 2017

Reception Immediately following in Mellon Institute Lobby

Nature becomes amazingly different from what we perceive with our eyes when zoomed in to the nanometer scale, where atomic spins interact and form diverse magnetic configurations. Besides holding great technological promise, magnetic nanostructures have also enabled a vibrant playground for fundamental physics—a thriving field known as spintronics. In this talk, I will introduce selected recent progress in spintronics that has reshaped our understanding of transport phenomena occurring at the microscopic scale. Special attention will be paid to antiferromagnetic...

The Kagome Lattice Heisenberg Model is one of the simplest realistic spin models with a quantum spin-liquid ground state. We discuss the current status of our understanding of this well-studied model. The precise nature of the spin-liquid state and the existence of a spin-gap in the model still remain in dispute. We also discuss experimental studies of Herbertsmithite material Kagome-antiferromagnet ZnCu_3(OH)_6Cl_2. We focus on NMR measurements by Imai and collaborators, who have presented strong evidence for a spin-gap in the excitation spectra. Through a Numerical...

Two-dimensional (2D) atomic crystals have emerged as a very attractive class of optoelectronic material due to the unprecedented strength in its interaction with light. In this talk I will discuss approaches to enhance the strength of this interaction even further using microcavities, and metamaterials. Specifically I will discuss enhancement of spontaneous emission [1], formation of strongly coupled exciton-photon quasiparticles (microcavity polaritons) [2], valley polarized polaritons and enhancement of nonlinear optical response from 2D transition metal...

Under gamma-ray or charged-particle excitation, scintillation light yield is a complicated function of carrier diffusion and cooling in the track along with kinetic rate terms depending on local excitation density. Up to 1021 electron-hole pairs/cm3 are produced in an initial track radius of about 3 nm. Extracting the fundamental rate constants directly from such conditions would require solving the diffusion and cooling problems in complex track structures first. Laser interband photon density response and time-resolved pump-probe studies are surrogate experiments that...

Nanotechnology is an interdisciplinary field focused on studying and manipulating ultraminiaturized structures, ones with at least one dimension 10,000 times smaller than the diameter of a human hair. This field has the potential to transform almost every aspect of our lives for the better – from enabling our cell phones and computers to run faster to generating our power more efficiently to making our tennis racquets and golf clubs lighter and more durable to making our medicines and drugs more efficacious. How can such small materials lead to such big advances in...

This talk will provide an overview of our group’s work using both standard and atypical high-performance computational chemistry modeling to elucidate atomic scale reaction mechanisms of catalytic reactions. I will introduce our toolkit of in silico methods for accurately modeling solvating environments and realistic nanoscale architectures. I will then present how these methods can be used for predictive insights into chemical and material design. The talk will then summarize our progress in unraveling reaction mechanisms for 1) electrochemical CO2 reduction with...