Gotham-Metro Condensed Matter Meeting

Gotham-Metro Condensed Matter Meeting

Friday, April 9, 2010

The New York Academy of Sciences

Presented By

 

New York is a city that never sleeps, and truly, the metropolitan area is constantly abuzz with breakthroughs in condensed matter physics. However, to date there has been little opportunity for physicists at the many institutions in the metro-area to come together to learn and share what is happening in our field. To fill this need, graduate students from the tri-state area have come together to organize the "Gotham-Metro Condensed Matter Meeting," and we want YOU to be a part of it. Hosted by the New York Academy of Sciences, this biannual conference is a fantastic chance for students, postdocs and faculty to share ideas and research with fellow physicists training and working in and around the Big Apple. The conference will include keynote lectures by distinguished speakers in both hard and soft condensed matter physics, a "fireside chat" led by a prominent local physicist, student talks highlighting current research, and poster sessions presenting research projects from diverse subfields, as well as a catered lunch and reception. With so many avenues for scientific discourse and collaboration, this is an event not to be missed!

Arrive early to participate in a breakfast workshop on how to network, presented by Science Alliance, the New York Academy of Sciences' career development program.

Scientific Organizing Committee

Darya Aleinikava

College of Staten Island, CUNY

Sara Callori

Stony Brook University, SUNY

Mauricio Campuzano

Stevens Institute of Technology

Eugene Dedits

College of Staten Island, CUNY

Lisa Dixon

New York University

Dmitri Efetov

Columbia University

Senia Katalinic

Rutgers University

Manas Kulkarni

Stony Brook University, SUNY;
Brookhaven National Laboratory

Jian Li

City College of New York, CUNY

Matt Lohr

University of Pennsylvania

Jason Merrill

Yale University

Stefan Natu

Cornell University

Peter Orth

Yale University

Sid Parameshwaran

Princeton University

Javad Shabani

Princeton University

Anil Shrirao

New Jersey Institute of Technology

Samarth Trivedi

New Jersey Institute of Technology

Chuck-Hou Yee

Rutgers University

Zhonghua Lukas Zhao

City College of New York, CUNY

Past Meetings

Gotham-Metro Condensed Matter Meeting Spring 2009
Gotham-Metro Condensed Matter Meeting Fall 2009

 

Agenda


8:30 AM

Poster Setup and Breakfast

Science Alliance Workshop: Introduction to Networking
Monica Kerr, The New York Academy of Sciences
10:00 AM

Hard Condensed Matter Keynote Presentation:
Quantum Imaging of Topologically Ordered Matter
Hari Manoharan, Stanford University

11:00 AMSession I Short Talks

Single-Frame Holographic Particle Image Velocimetry
Lisa Dixon, New York University

Carbon Nanofilms on Insulating Substrates
Sergey V. Samsonau, The College of Staten Island/CUNY

11:30 AM

Coffee Break

12:00 NOONSession II Short Talks

Transport Experiments with Dirac Electrons
Joseph Checkelsky, Princeton University

Landau Level Quantization and Slow-Down of Electrons in Twisted Graphene Layers
Adina Luican, Rutgers University

Proposed Physical Mechanism of Chromosome Segregation in Caulobacter Crescentus
Edward J. Banigan, University of Pennsylvania

Characterization of Graphitic Thin Films and Top-Gated Klein Transistors
Milan Begliarbekov, Stevens Institute of Technology

1:00 PM

Lunch (provided)

2:00 PM

Soft Condensed Matter Keynote Presentation:
Microfluidics for Making and Studying Soft Materials
David Weitz, Harvard University

3:00 PM

Poster Session

4:15 PM

"Fireside Chat"
R. Shankar, Yale University

5:00 PM

Reception

Speakers

Keynote Speakers

Hari Manoharan

Stanford University

Manoharan received his PhD from Princeton University in 1997. Manoharan joined Stanford University in 2001 as an Assistant Professor of Physics and in 2010 became an Associate Professor. His awards include Hertz Foundation Fellow (1991-96), IBM Invention Achievement Award (2000), ONR Young Investigator (2002-2004) and the NSF Career Award (2002-2006) to name a few.

R. Shankar

Yale University

R. Shankar received his PhD in Electrical Engineering from the Indian Institute of Technology in 1969 and his PhD in Elementary Particle Physics from Berkeley in 1974. After three years at the Harvard Society of Fellows, he joined Yale's faculty, which he chaired between 2001-07and where he is the John Randolph Huffman Professor of Physics. He switched to condensed matter in 1982 and has been free of infinities ever since, though he goes for frequent checkups to make sure.

David Weitz

Harvard University

Weitz received his PhD from Harvard. He worked at Exxon Research and Engineering as a research physicist for nearly 18 years, and then became a Professor of Physics at the University of Pennsylvania. He moved to Harvard about 11 years ago, and is currently Professor of Physics and Applied Physics. He is also the director of Harvard's Materials Research Science and Engineering Center and co-director of Harvard's Kavli Institute for Bionano Science and Technology. He helped arrange the establishment of the BASF Advance Research Initiative at Harvard, which he co-directs.

Workshop Speaker

Monica Kerr

The New York Academy of Sciences

Speakers

Edward J. Banigan

University of Pennsylvania

Milan Begliarbekov

Stevens Institute of Technology

Joseph Checkelsky

Princeton University

Lisa Dixon

New York University

Adina Luican

Rutgers University

Sergey V. Samsonau

The College of Staten Island/CUNY

 

Abstracts

Science Alliance Workshop:  Introduction to Networking

Monica Kerr, PhD, Director of Science Alliance at the New York Academy of Sciences

In preparation for this meeting, you have likely read the latest scientific articles in the field and scoped out the most interesting talks and posters. Perhaps you have also thought about pursuing a collaboration with another lab, getting your hands on an important tool or reagent, or even finding that all-important postdoc position! But if the thought of networking makes you want to hide behind the posters or cheese dip, join us over breakfast for a fun and interactive session that will show you that building your professional network does not have to be intimidating, all you need is a little advance preparation. You will learn the skill of developing an ‘elevator speech’ and will have the opportunity to practice your own before embarking on the meeting. In advance of the session, you may want to think about someone you would like to network with in order to make the exercises that you will be doing more concrete.

Quantum Imaging of Topologically Ordered Matter

Hari Manoharan, PhD, Stanford University

Deforming a material and restoring it precisely back to its starting point intuitively implies that the material before and afterwards is identical. This is true classically, and was believed to be true in general until recently in the history of quantum mechanics. Even if all the atoms, electrons, and other ingredients are returned exactly to where they started, we now know that the restored material can differ from the undeformed material by nontrivial quantum mechanical phase factors. These geometric or Berry phases have garnered increasing appreciation in recent years, and in condensed matter they arise from the topology of electronic states and embedded degeneracies. Such considerations have helped to identify new ground states consisting of topologically ordered matter, which on a practical level can be exploited in quantum devices and quantum computing strategies. This talk will overview new experiments from our lab, employing scanning tunneling microscopy and atomic manipulation, that directly visualize and control topological order in several materials and nanostructures.

Mircofluidics for Making and Studying New Soft Materials

David Weitz, PhD, Harvard University

Microfluidic devices offer a new way of very precisely controlling the flow and mixing of fluids. These can be used to create new and interesting structured fluids. They can also be used for novel biotechnological applications. These will be described.

Fireside Chat

Prominent physicist, R. Shankar, PhD of Yale University, will lead this interactive discussion with the audience. The topic of discussion may range from the speaker's views on the future of physics in the US to stories depicting adventures in research.

Short Talks

Single-Frame Holographic Particle Image Velocimetry

Lisa Dixon, Fook Chiong Cheong and David G. Grier, New York University

We present a novel method for single frame particle image velocimetry of micron scale spheres based on holographic video microscopy. Our approach takes advantage of the blurring that recorded holograms suffer when a sphere moves during the exposure period of the camera. By measuring the angular variance in intensity of the blurred hologram, we extract a model-independent metric for the particle velocity. We find this to be accurate for speeds that permit characterization of other properties of the sphere, such as radius and refractive index through Lorenz-Mie mocroscopy. Single-frame holographic velocimetry yields information on the dynamics of a particle, without sacrificing any other measurements.

Carbon Nanofilms on Insulating Substrates

S.V.Samsonau and A.M. Zaitsev, The College of Staten Island/The City University of New York

Methods of growth of uniform highly conductive carbon nanofilms on large area insulating substrates remain the major challenge of anticipated carbon-based nanoelectronics. Development of such a method is the aim of the presented research. Carbon nanofilms were grown by the catalyst-assisted deposition from methane on diamond, sapphire and quartz substrates at temperatures in the range from 650 to 900ºC. A specially designed all-graphite furnace was use for experiments. Kinetic of the growth was monitored by in-situ measurements of conductance of the growing films. In order to assess the type of conductance of the nanofilms, the temperature dependence of their conductance was measured from room down to liquid nitrogen temperature. The temperature dependence of conductance indicates that the carbon nanofilms consist of amorphous (semiconductor-like) and metallic carbon. The developed method of growth of carbon nanofilms promises to be inexpensive and compatible with existing Si-wafer based electronic technology.

Transport Experiments with Dirac Electrons

J. Checkelsky, L. Li, N.P. Ong, Y.S. Hor and R.J. Cava, Princeton University

Dirac electrons, charged spin ½ particles which are characterized by a linear energy-momentum dispersion relation, have been recently shown to exist in solid state systems. The surface of the 3D topological insulators and the 2D system graphene are two such systems. The ubiquity of quantum spin Hall physics and protected, current carrying states in low-dimensional Dirac systems has driven interest in observing transport currents in these materials. Transport experiments are presented here characterizing both systems to high magnetic fields. First, we report an insulating state induced in graphene at the Dirac point in magnetic field indicating that the protected states can be destroyed. Second, in the topological insulator Bi2Se3 we report conducting, metallic in-gap states. This demonstrates the existence of robust current carrying modes originating from the surface band structure.

Landau Level Quantization and Slow-Down of Electrons in Twisted Graphene Layers

Adina Luican1, Guohong Li1, Alfonso Reina2, Jing Kong2, Rahul R. Nair3, Kostya S. Novoselov3, Andre. K. Geim3, and Eva.Y. Andrei1, 1Rutgers University, 2MIT, 3University of Manchester, UK

A twist between stacked graphene layers produces a super-lattice which for certain rotation angles gives rise to Moiré patterns. These patterns are often seen in STM images, but their effect on the electronic properties is not fully understood. Using scanning tunneling microscopy and spectroscopy, we obtain direct evidence for the electronic structure of twisted graphene layers. The samples were suspended membranes of CVD grown graphene which contain areas with various rotation angles. We find that the density of states on twisted layers develops two Van Hove singularities that flank the Dirac point at an energy that is proportional to the twist angle [1]. In the presence of a magnetic field the density of states develops quantized Landau levels (LL) characteristic of massless Dirac fermions. From the energy and field dependence of the LL sequence we obtain the Fermi velocity and find that it is renormalized by an amount that depends on the angle of rotation. These results are compared with theoretical predictions.

[1] Li, G.; Luican, A.; Lopes dos Santos, J.M. B.; Castro Neto, A. H.; Reina, A.; Kong, J.; Andrei, E.Y. Observation of Van Hove singularities in twisted graphene layers. Nature Physics 2010, 6, 109-113.

Proposed Physical Mechanism of Chromosome Segregation in Caulobacter Crescentus

Edward J. Banigan, University of Pennsylvania, Michael Gelbart, Princeton University, Zemer Gitai, Princeton University, Andrea J. Liu. University of Pennsylvania and Ned S. Wingreen, Princeton University

Chromosome segregation is a fundamental process for all cells, but the force-generating mechanisms that drive chromosome movements in bacteria are especially unclear. In Caulobacter crescentus, recent work has demonstrated that a structure made up of the ParA protein elongates from one cell pole and interacts with ParB, a protein binding to the chromosome near the origin of replication (ori). ParB disassembles ParA, causing ParA to pull ParB, and thus, the ori to the opposite end of the cell. We performed Brownian dynamics simulations of this system in order to uncover the physical mechanism of this motion. We find that motion of the ori is robust to several variations of the model as long as a steady-state concentration gradient of ParA is established in the moving frame of the ParB-decorated chromosome. We suggest that the mechanism is "self-diffusiophoretic'': by disassembling ParA, ParB creates a concentration gradient of ParA so that the ParA concentration is higher in front of the chromosome than behind it. Since the chromosome is attracted to ParA via ParB, it moves up the gradient in the desired direction.

Characterization of Graphitic Thin Films and Top-Gated Klein Transistors

Milan Begliarbekov, Onejae Sul, Nan Ai, Chen-En Tsai, Johanna Heureaux, Eui-Hyeok Yang, and Stefan Strauf, Stevens Institute of Technology

Single and few layer graphitic thin films are very promising for future applications in nanoelectronics and provide an ideal material for the study of quantum transport phenomena. We employed Raman spectroscopy in order to perform layer metrology and identify the number of constituent graphene layers which have been micromechanically exfoliated from natural graphite. Furthermore, we have directly identified zigzag and armchair edges by their characteristic Raman signatures caused by the Kohn anomalies in the graphene spectrum. Building on these results we have fabricated top-gated graphene field-effect transistors by electron beam lithography, which consist of lateral source and drain contacts and an electrically insulated top gate of 50 nm width fabricated on top of a 10 nm aluminum-oxide dielectric layer. Two terminal measurements were then carried out to determine the location of the Dirac point. A room temperature mobility of 3700 cm2V-1s-1 was determined from the transconductance measurements. An n-p-n transistor geometry was created by electrostatic biasing of the top gate with respect to the substrate, which acts as a global back-gate. In this configuration we observed the characteristic signature of chiral Klein tunneling at 4K. The magnitude of Klein-tunneling decreases with increasing temperature until it ceases at around 66 K in our device. The observation of Klein tunneling in these structures is useful in ascertaining the ballistic mean free path for future studies of coherent transport phenomena.

Travel & Lodging

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The New York Academy of Sciences

7 World Trade Center
250 Greenwich Street, 40th floor
New York, NY 10007-2157
212.298.8600

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