# Presentation: 106484

## Graphene: You can never be too thin, or too rich. (Mrs Simpson)

- When it was discovered in 1980, the quantum Hall effect was a fragile quantum phenomenon requiring temperatures close to absolute zero. Material improvement and electron density optimization had pushed the temperature of its existence to about -240oC. The advent of a new two-dimensional material, graphene, has opened up new possibilities for 2D physics in general and for the QHE in particular. We have now observed the QHE in graphene at room temperature, bringing this previously low temperature phenomenon to our human temperature scale.
- Science, vol. 315,  page 1379, 2007.
- The quest to understand  graphene  is greatly advanced by  measurement of vibrations of the carbon atoms that drag mobile electrons with them. The combined oscillation of neutral atoms and electrons  reveals clues on unique electrical conduction in this extreme limit of a single atomic layer. Measurements of vibration modes emerge as  primary tools to explore fundamental physics and materials science of graphene.
- Physical Review Letters, vol.98, page 156805, 2007

_**Graphene: **__**You can never be too thin, or too rich**__**.**_** ****(Mrs Simpson)**

- Aron Pinczuk – Horst Stormer, Columbia University, DMR 0352738

**Notes:**
Significance:
The quantum Hall effects in semiconductor heterostructures of great perfection and, very  recently, in graphene (a single atomic layer of carbon atoms) are macroscopic manifestations of emergent electron fluids with characteristic low-lying collective excitations. The research supported by this award aims at discovering and understanding exotic quantum phases  in such two-dimensional electrons systems as they appear in magneto-transport and by inelastic light scattering measurements of collective modes. 
The fluids of the fractional quantum Hall effect are currently understood as composed of nearly free composite fermion quasiparticles in which electrons capture even numbers of quanta of magnetic flux. The light scattering experiments revealed  from free to interacting composite fermions that requires closer examination of the highly successful free composite fermion model. 

## Graphene: You can never be too thin, or too rich. (Mrs Simpson)

-  **Education:**
- Three graduate students (Erik Henriksen, Trevor D. Rhone and Jun Yan) and three postdocs (Dr. Yann Gallais, Dr. Javier Groshaus,  and Dr. Zhigang Jiang)  contribute to research supported by this NSF award. Altogether 5 undergraduate students are involved in the program and are sharing authorship ( Mollie Schwartz, Sarah Goler, Maika Takita, Ken Sipes andTheresa Villarson.)
- Beyond exploring the frontiers of many particle quantum physics, students and postdocs are being trained in ultra low temperature techniques, semiconductor physics, material processing and clean-room methods. The expertise gained by the principle investigators flows into the physics curriculum at Columbia, where Pinczuk teaches condensed matter physics and Stormer teaches a university wide freshman class including nano-science and quantum mechanics.

- Aron Pinczuk – Horst Stormer, Columbia University, DMR 0352738

**Societal Impact:**
- _Electronics of the future? _
- The novel two-dimensional conductor graphene exhibits very unusual new physics. Yet it also is being considered as the basis for future electronic devices that may lead us beyond the limitations of the present technology. Our research helps laying the groundwork for such explorations.

- Columbia graduate and undergraduate students working on graphene physics

_**Graphene: **__**You can never be too thin, or too rich**__**.**_** ****(Mrs Simpson)**

**Notes:**
Educational:
This program involves students and postdocs of Columbia University in research efforts that create outstanding opportunities to work at frontiers of condensed matter science. It offers participants access to the expertise from Columbia U., Bell Labs (Lucent Technologies), Princeton U., the National High Magnetic Field Lab,and  U. Florida. The program has major links with prestigious institutions outside the U.S, such as the Scuola Normale Superiore (Italy) and the Weizmann Institute (Israel). 

Impact:
We seek the discovery of new quantum phases in strongly interacting electron systems. The studies are carried out in artificial semiconductor structures that greatly advance state-of-the-art methods used in fabrication of ultra-thin semiconductor structures. There is here a unique combination of new fundamental physics with impacts that may revolutionize areas of electronics, optoelectronics and information processing.  
The recent observations of quantum Hall effect in graphene, in which one of the PI’s is a co-author, has moved the quantum Hall realm to the extreme single atomic layer limit. This extraordinary advance provides us with laboratory systems that greatly expand frontiers and create solid expectations for exciting discoveries.