From Crumpling Geometries to Graphene Materials: 5th Gotham-Metro Condensed Matter Meeting 2011

Overview

Researchers in the field of condensed matter physics study phenomena that emerge from the interactions of systems with many degrees of freedom. In this spirit, the April 15, 2011, Gotham-Metro Condensed Matter Meeting at the New York Academy of Sciences brought together physicists from the New York metropolitan area to hear about each other's work and to share their own. At this graduate student-organized meeting, students, post-docs, and professors heard about cutting-edge research in the speaker presentations and poster session, and no less importantly, engaged in informal discussions throughout the day.

In the soft matter keynote address Tom Witten of the University of Chicago described the physics of crumpling. It turns out there is a fascinating interplay between geometry and physics in the seemingly mundane crumpling of a piece of paper. At first, it seems surprising that folds and vertices spontaneously form in the crumpled paper since locally they have a very high energy cost due to their large curvature. However, Witten explained, the global energy of the system is reduced by localizing the high curvature to the folds and vertices. This is an example of energy condensation, which is seen in many different fields, such as gravitational systems, turbulence, and phase transitions.

Paul McEuen of Cornell University spoke about advances in graphene physics in his hard matter keynote address. Graphene is a single atom-thick, highly ordered layer of carbon. It is a remarkable material, with interesting electric, optical, and mechanical properties. For instance electrons in graphene behave like relativistic Dirac particles, and the material's optical transmittance is determined by fundamental constants. McEuen described new fabrication methods for the material and explained how, mechanically, graphene sheets can behave like a drumhead. Finally McEuen explored possibilities for using graphene to make new advances in electronics or to help create a whole new field of nanotechnology and micro-machines.

Nobel laureate Philip W. Anderson of Princeton University spoke about and entertained questions regarding his experience searching for a deeper understanding of nature. He related some of the great biologist Francis Crick's thoughts about principles by which theorists should abide. One interesting conclusion is that many great discoveries are "Columbus" type discoveries. These discoveries are made precisely because there is some flaw in the logic of the approach, and the findings are not immediately appreciated for what they really are. One example he described was the discovery, made using an incorrect theory, of the A phase in superfluid ³He. Anderson recommended that one would do well to concentrate on the experimental anomalies, instead of sweeping them under the rug. In the anomalies are the clues that lead to the break-through discoveries, he said.

In addition to the keynote addresses there were student talks highlighting an array of interesting research going on around New York. These talks were shorter, which allowed for a greater range of topics to be discussed. In addition, these talks gave the audience the opportunity to query student and post-doc presenters on the specifics of the experiments they performed, and this line of questioning generated discussion about practicable directions for future research. One highlight of these presentations was the talk by Bryan Chen from the University of Pennsylvania who gave an interesting description of the topology of bubbles in a 2-D foam. Another highlight was the talk by Stefano Sacanna from New York University who described his work with cubic colloids and the physics of the crystals they can form.

Darya Aleinikava of CUNY, Staten Island, described superclimb (non-conservative motion (climb) assisted by superflow along its core) of dislocations in solid ⁴He. Senia Coh of Rutgers University discussed her work using direct and inverse photoemission to measure the electronic structure and energy level alignment of several zinc tetraphenylporphyrin derivatives adsorbed on TiO₂ (110) and ZnO (11-20) surfaces. Arijeet Pal of Princeton University discussed the measures his group uses to probe some of the properties of the ergodic phase and the localized phase that arise in a generic, isolated, interacting quantum spin system at high energy densities. Yashwant K. Verma of Stevens Institute of Technology reported on his group's technique for creating macroscopically ordered aggregates of strongly-coupled colloid QDs (quantum dots) suspended in a matrix of nematic liquid-crystal molecules at room temperature.

The range of topics presented during the poster session was expansive. Students presented on everything from non-affine deformations in flexible polymer gels to quantum phases in the quantum hall regime.

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