|Physics hosts colloquiums Thursday and Friday|
Physics will host two colloquiums March 4 and 5. The first colloquium, titled "How more is different correlated quantum matter away from equilibrium," will feature Maxim Dzero, Physics, University of Maryland, at 4 p.m. Thursday, March 4, in 211 Witmer Hall. Coffee and Cookies will be served at 3:30 p.m. in 215 Witmer Hall.
Abstract: Traditionally, physicists are interested in studying new phases of matter. Superconductors, superfluids, ferromagnets, liquid crystals are a tribute to the extraordinary capability of matter to acquire new forms and properties. Over past decade, researchers working in condensed matter physics have studied a new kind of phase transitions that emerge in correlated matter out of equilibrium. Contrary to naive expectations, quantum matter driven far from equilibrium can acquire phases completely different from its ground state counterparts. In this talk, the speaker will describe the results of our recent efforts to understand the formation of novel states in quenched superfluids. For a particular set of initial conditions, he will discuss two new states of matter: (a) gapless steady state and (b) spatially modulated steady state emerging due to the Cooper pair turbulence and describe the experiments that can probe these states. He will also make connections between our theory and theories describing the "cosmological experiments" of defect formation in the early Universe.
The second colloquium, titled "Wrinkling and Strain Softening in Thin Supported Membranes of Single-Wall Carbon Nanotubes," will feature Erik K. Hobbie, Physics, NDSU, at 4 p.m. Friday, March 5, in 211 Witmer Hall. Coffee and Cookies will be served at 3:30 p.m. in 215 Witmer Hall.
Abstract: Thin membranes of single-wall carbon nanotubes (SWNTs) show considerable promise for a number of potential applications. The high conductivity and shape anisotropy of the nanotubes enable the formation of conductive quasi-2D networks at remarkably low surface density, and the mechanical characteristics of the individual SWNTs can be outstanding. Recent advances in the separation of SWNTs by length and electronic type allow for the production of films and coatings with precisely tunable properties, and the tremendous potential of these films for flexible-electronics applications demands a deeper understanding of the coupling between deformation, microstructure and charge transport. Compressive wrinkling has recently emerged as a powerful tool for engineering and characterizing thin films supported by soft flexible substrates, and we use this approach here to study the nonlinear deformation mechanics of membranes assembled from purified SWNTs. Our measurements reveal a material that is remarkably stiff under infinitesimal deformation but softens dramatically at finite strain. We link this strongly non-linear behavior to an upward shift in percolation threshold triggered by strain-induced nanotube alignment, an effect correspondingly apparent as an anisotropic decrease in conductivity. Our results are in agreement with theoretical models of percolation in anisotropic 2D rigid-rod networks.
-- Connie Cicha, Administrative Secretary, Physics & Astrophysics, email@example.com, 777-2911