Proposal for a Workshop at the Aspen Center for Physics Summer 2008

Organizers:

Prof. Antonio H. Castro Neto (contact person) Department of Physics Boston University 590 Commonwealth Ave. Boston, MA, 02215 Phone: 617-353-6116 Email: [email protected]

Prof. Alessandra Lanzara (responsible for working to ensure diversity) Department of Physics University of California Berkeley 321 Birge Hall Berkeley, CA 94720-7300 USA Phones: (510) 642-4863 (campus) (510) 486-5303 (LBL) Email: [email protected]

Prof. Allan MacDonald Department of Physics University of Texas at Austin 1 University Station C1600 Austin, Tx 78712-0264 Phone: 512-232-9113 Email: [email protected]

Title: The Physics of Graphene

Rationale: The discovery of an anomalous integer quantum Hall effect in graphene (a form of two-dimensional carbon) by two independent groups (K.S. Novoselov et al., Nature 438, 197 (2005), and Yuanbo Zhang et al., Nature 438, 201 (2005)) has stirred a lot of interest in the scientific community (see, for instance, Nature “News and Views“ by C. Kane, Nature 438, 168 (2005), and http://physicsweb.org/articles/news/9/11/6/1) as well as in the international media (see, for instance, a BBC News Report on the subject: http://news.bbc.co.uk/1/hi/sci/tech/3944651.stm). The excitement behind this discovery has two main driven forces: basic science, and technological implications.

The excitement on graphene can be measured by the numbers of manuscripts written on the subject. In Fig.1.1 we show the number of articles posted on the cond-mat arXiv.org server from 1998 till 2007 containing the word of graphene in the abstract. One can clearly see that there is an exponential growth in the literature since the publication of the papers by Geim and Kim’s groups.

Graphene is a condensed matter realization of the Dirac equation since the electronic dispersion close to the Brillouin zone edges are conical with a Fermi-Dirac velocity of order of one hundredth of the velocity of light (see, for instance, Drawing conclusions from graphene by A. H. Castro Neto, F. Guinea and N.M. R. Peres, Physics World 19, 33 (2006), http://physicsweb.org/articles/world/19/11/7/1). Hence, unlike most of other solids, graphene electrons cannot be described in terms of an effective mass. This fact has strong implications in many of the physical properties of these systems: the electronic density of states vanishes at the Fermi level, there is very poor screening of the Coulomb interaction, the Dirac fermions interact very strongly with disorder such as vacancies, and Landau’s Fermi liquid theory is not applicable. That is, graphene is a non- Fermi liquid system. In fact, graphene share many properties with quasi-two-dimensional d-wave superconductors (such as superconducting cuprates) who can also be described in terms of Dirac-like excitations. As a result of this exotic behavior, graphene has unusual collective excitations (such as zero modes), and an anomalous integer quantum Hall effect with a finite Berry’s phase. There has been an intense experimental effort in recent months in graphene research. Cutting-edge research techniques such as infrared absorption, angle resolved photo-emission (ARPES), scanning tunneling microscopy (STM), and neutron scattering, are being used to study this system. Some of these techniques that have been used so successfully in high temperature superconductivity research, can be directly applied to these materials that also show layered structure. Because of its high electronic mobility, structural flexibility, and capability of being tuned from p-type to n-type doping by the application of a gate voltage (see, K. S. Novoselov et al., Science 306, 666 (2004)), graphene is being considered a breakthrough in terms of carbon-based nano-electronics. In fact, unlike carbon-nanotubes, graphene can be easily patterned with standard lithographic techniques and does not present problems with electric contacts. With the predicted saturation in silicon-based technology due to limitations in miniaturization, integration, yield enhancement, and inter- connectivity (see, for instance, the International Technology Roadmap for Semiconductors, http://www.itrs.net/Common/2004Update/2004Update.htm), there is a growing interest by technology development companies in graphene research. The interest in the anomalous properties of graphene only adds to the intriguing discovery that graphite (a crystal made out a stack of graphene layers) can be made ferromagnetic when sufficiently disordered (see, for instance, the focus page of American Physical Society in 2003, http://focus.aps.org/story/v12/st20). This discovery still remains unexplained theoretically (even in fact of many proposals) and has drawn a lot of attention to modern carbon research (see http://physicsweb.org/article/news/5/12/11\#11, and http://nanotechweb.org/articles/news/3/3/13 ). It is quite clear to us that graphene research is in exponential growth. Because of its tradition, infrastructure, and location, the Aspen Center for Physics is in a special position to host the first international workshop in graphene research in the summer of 2008. We have assembled a list of participants that represents respected scientists who are currently doing significant in the field. We expect that this list will change with time until the date of the workshop.

Proposed dates: 16 June – 4 July (preferred); 23 June – 11 July (acceptable); 14 July – 8 August (acceptable).

Proposed Participants (in alphabetical order):

B. L. Altshuler (Columbia University, USA); T. Ando (Tokyo Institute of Technology, Japan); Eva Andrei (Rutgers University, USA); Reza Asgari (Tehran); Alexander Balatsky (LANL, USA); G. Baskaran (IMS, India); Dmitri Basov (University of California at San Diego, USA); Yarsilav Blanter (Delft, The Netherlands); Carlo Beenakker (Leiden, The Netherlands); Claire Berger (Laboratoire d'Études des Propriétés Électroniques des Solides, France); Arne Brataas (Trondheim); Luiz Brey (ICCM, Spain); J. P. Carbotte (McMaster, Canada); M.W.C. Dharma-wardana (NRC-Canada) Walt de Heer (Georgia Institute of Technology, USA); Millie Dresselhaus (MIT, USA); Konstantin Efetov (Bochum, Germany); W. Falko (Lancaster University, UK); Eduardo Fradkin (University of Illinois at Urbana-Champaing, USA); Andre Ferrari (Oxford, England); Herb Fertig (Indiana University, USA); H. Fukuyama (University of Tokyo, Japan); Victor Galitski (University of Maryland, USA); Andre Geim (University of Manchester, UK); Mark Goerbig (Orsay, France); Bennett Goldberg (Boston University, USA); Francisco Guinea (Instituto de Ciencia de Materiales de Madrid, Spain); G.-H. Gweon (University of California at Berkeley, USA); Duncan Haldane (Princeton University, USA); Ayako Hashimoto (Tsukuba University, Japan); Igor Herbut (Simon Fraser, Canada); Euyheon Hwang (University of Maryland, USA); Mihail Katsnelson (Nejimegen, The Netherlands); Eun-Ah Kim (Stanford University, USA); Philip Kim (Columbia University, USA); D. Khveshchenko (Chapel Hill, USA); Valeri Kotov (Boston University, USA); Yakov Kopelevich (Unicamp, Brazil); Jeannie Lau (University of California at Riverside, USA); Patrick A. Lee (MIT, USA); L. S. Levitov (MIT, USA); S. Louie (University of California at Berkeley, USA); Maria Pilar Lopez-Sancho (ICCM, Spain); Charles Marcus (Harvard, USA); Ivar Martin (LANL, USA); P. L. McEuen (Cornell, USA); A. Morpurgo (Delft, The Netherlands); Y. Niimi (University of Tokyo, Japan); Cristiane Morais-Smith (Utrecht, The Netherlands); E. Mucciolo (Central Florida University, USA); Kentaro Nomura (University of Texas at Austin, USA); K. Novoselov (University of Manchester, UK); J. Nilsson (Leiden, The Netherlands); Tami Pereg-Barnea (University of Texas at Austin, USA); Vitor Pereira (Boston University, USA); Nuno Peres (University of Minho, Portugal); F. M. Peeters (Antwerpen, Belgium); Aron Pinczuk (Columbia University, USA); Marco Polini (INFM, Italy); Elsa Prada (Karlshure, Germany); Subir Sachdev (Harvard University, USA); K. Sengupta (Saha Institute, India); Sankar das Sarma (University of Maryland, USA); Ramamurti Shankar (Yale University, USA); Elena Stolyarov (Columbia University, USA); Y.-W. Son (Berkeley, USA); Joao Lopes dos Santos (University of Porto, Portugal); S. G. Sharapov (MacMaster University, CA); Manfred Sigrist (ETH, Zurich); H. L. Stormer (Columbia University, USA); Anna Swan (Boston University, USA); Shan-Wen Tsai (University of California at Riverside, USA); B. Uchoa (Boston University, USA); Oskar Vafek (Florida State University, USA); Maria Vozmediano (ICCM, Spain); Katsunori Wakabayashi (Hiroshima University, Japan); Y. Zhang (Berkeley, USA); S. Zhou (University of California at Berkeley, USA); K. Ziegler (Augsburg, Germany).