Events

Science and technology are strongly influenced by light-matter interactions in materials that comprise real optoelectronic devices. The designs of these devices can be enhanced using knowledge of the fundamental electronic dynamics and dephasing processes. Ultrafast pulsed laser experiments provide a snapshot of these fundamental processes, and tailoring the excitation pulses allows for coherent control of the light-matter interactions.

Coherent optical control of optoelectronic, photonic and quantum electronic materials is useful because it elicits information about fundamental physical processes. It also providing better knowledge of how these materials behave when incorporated into nanoscale and quantum devices. Here, I demonstrate quantum interference between single and two-photon absorption pathways in semiconductors. This injected and controls transient currents that are detected by terahertz emission.

Graduate and undergraduate student lunch with Alan Bristow

Biomolecules perform fascinating functions essential for all life forms, including disease states upon perturbation or mutation. In order for existing biomolecular complexes to achieve optimal performances or to engineer new ones to execute targeted activities, a deep “bottom-up” understanding of the connection between the fundamental molecular mechanism and biological functions is required.

Observing the vibrational spectra of biomolecules in real time offers the exciting possibility to track ultrafast structural dynamic changes of the photoexcited chromophore if by stimulated Raman, or conformational dynamics of protein residues if extending into the IR regime and going multidimensional.

Undergraduate and graduate students meet with Chong Fang

The terahertz (THz) electromagnetic wave frequency range - broadly defined as 0.1 – 30 THz (3 mm – 10 µm wavelength) - is at the interface of modern electronics and optics. This electromagnetic spectrum has been much less explored and has been called the “terahertz gap” due to the lack of efficient, room-temperature sources and detectors. Despite these difficulties, there has been recent explosion of interest in using THz pulse to address many questions in electrical engineering, physics, chemistry, and material sciences.

One of the most important aspects of contemporary semiconductor physics is an understanding of charge conduction process. Terahertz (THz) spectroscopy provides a non-contact electrical probe, thus circumvents many constraints of conventional electrical measurement techniques. In this light, I will discuss two exemplary applications of THz spectroscopy:
1. Dirac Fermion dynamics in graphene
2. Electronic transport dynamics in quantum cascade lasers

Graduate & undergraduate student lunch with Dr. Hyunyong Choi

Grad and undergrad student lunch with Dr. Alipasha Vaziri.

TBA

Dr. Vzairi will discuss plans for future research.

I am interested in the role that mechanical forces play in biology. Nature has exploited the intrinsic physical properties of polymers to build networks of biopolymer filaments and associated proteins, called the cytoskeleton, which can exert the tensile and contractile forces within cells required for cell functions such as cell motion and cell division. I will present results from experiments using reconstituted cytoskeletal biopolymers to investigate how these filaments define intracellular organization and mechanics.

Cells must not only generate forces to move and divide, but they must also be able to react to forces in their environment. This conversion of physical forces into biological responses is known as mechanotransduction. I will describe measurements of the response of living Escherichia coli bacteria to osmotic stress as a model for mechanotransduction, and of the mechanical properties of a cytoskeleton system reconstituted from purified components as a model for the behavior of cells.

Graduate and undergraduate student lunch with Dr. Maria Kilfoil

BaCuChF (Ch = S, Se, Te) materials are chalcogen-based transparent conductors with wide optical band gaps (2.9 – 3.5 eV) and a high concentration of free holes (1018 – 1020 cm-3) caused by the presence of copper vacancies. Chalcogen vacancies compensate copper vacancies in these materials, setting the Fermi level close to the valence band maximum. BaCuChF thin film solid solutions prepared by pulsed laser deposition (PLD) have tunable properties, such as lattice constants, conductivity and optical band gaps.

Biomagnetics: An interdisciplinary field where magnetics, biology and medicine overlap

Shoogo Ueno
Kyushu University/Teikyo University/The University of Tokyo

One of the current frontiers in magnetism is to understand the domain structure and the magnetization reversal
in nanometer sized particles. Explorations at these length scales have been aided by the development of new
magnetic imaging techniques [1] one of which is the magnetic force microscope (MFM), a variant of the atomic
force microscope. We have utilized the high resolution MFM (30 nm) we developed [2] to increase our
fundamental understanding of magnetism on this length scale. We will discuss the magnetic reversal of chains

FEI, Hillsboro is hosting a a day of exploration for OSU Physics grad and undergrad students by opening up its lab. The visit will provide insights into the possibilities for a career in physics, but it is not a recruiting function. Lunch and refreshments will be provided.

The plan is to introduce FEI to the group, provide presentations on the technology and how people with physics backgrounds contribute to FEI's business. Following that will be an

A microscopic understanding of the Ferromagnetic/Antiferromagnetic (F/AF) direct exchange coupling
or exchange biasing has been elusive for the over 45 years since its was discovered. In part, the almost
exclusive use of hysteresis loops to study the phenomenon has limited our understanding. A new experimental
technique was developed to study the exchange coupling between a ferromagnet and antiferromagnet [Appl.
Phys. Lett. 69,3932-3931 (1996)]. This new technique has enjoyed considerable success in explaining many