Events at Physics |
Events on Tuesday, March 10th, 2009
- R. G. Herb Condensed Matter Seminar
- Single-Particle Properties of Graphene: Magnetotransport and Superlattice-Controlled Band Gap
- Time: 10:00 am
- Place: 5310 Chamberlin
- Speaker: Rakesh Tiwari, Ohio State University
- Abstract: Graphene, a two-dimensional form of carbon, is poised to play an important role in future electronic devices. In this talk I will discuss two properties of graphene which may be very useful for next-generation devices: large magnetoresistance and the controllable band gap at the Dirac point. I will show that the experimentally observed large magnetoresistance can be explained using a picture of graphene as a mixture of n and p type puddles. Even if we assume a field independent resistivity for the individual puddles (free electron or hole picture), an effective medium approximation predicts a large magnetoresistance for the composite, in agreement with experiment. In the second part of the talk, I will describe an efficient way of controlling the electronic band gap at the Dirac point in graphene using a non-centrosymmetric superlattice potential. I will confirm this method by calculating the superlattice band structure using an expansion of the wave functions in plane waves.
- Host: Robert Joynt
- Chaos & Complex Systems Seminar
- Engaging the flow: a creative dialogue revisited
- Time: 12:05 pm
- Place: 4274 Chamberlin
- Speaker: Harry Webne-Behrman, UW Office of Human Resource Development
- Abstract: Creative conversations don't mechanically follow 'outline form,' they emerge from the synergies and interactions of participants in hard-to-predict ways. Is there a way to facilitate such dialogues, rather than direct them, so 1 + 1 >2? Is there a way to capture the creative ideas that emerge? Last Fall, the Chaos & Complexity Seminar engaged in a creative dialogue around a broad question with some productive ideas. On this occasion, the group is asked to focus more deeply on one of the issues that emerged from the previous dialogue: "How might UW-Madison best engage its resources to meet the challenge of assuring the "Wisconsin Experience" for its students?" The Wisconsin Experience is intended to result in graduates who have the capacity and commitment to make the world a better place. It is intended to build upon the unique strengths of the UW-Madison community to foster such ideals that have resulted in extraordinary citizens, global activists and volunteers, corporate leaders and others with a special sense of social responsibility and an activated, current sense of the Wisconsin Idea. My intention in this dialogue is to gain participant reflections on this initiative in its pedagogical, research, service, and cultural dimensions. What aspects of this Experience are worth pursuing? Where should resources be emphasized and how might they best be organized to do so? For additional information about this important initiative from Aaron Brower (Vice-Provost for Teaching and Learning) and Lori Berquam (Dean of Students), please visit: http://www.learning.wisc.edu -- a summary of the objectives of the Wisconsin Experience is attached, as well. Join us for fascinating conversation and see what happens!
- Astronomy Colloquium
- The Local Group Manifesto
- Time: 3:30 pm
- Place: 6515 Sterling Hall
- Speaker: Kathryn Johnston, Columbia University
- Abstract: In the context of Lambda CDM, while larger structures in the Universe are thought to form hierarchically from the mergers of many smaller structures, the histories of individual galaxies are expected to vary widely. This raises the question of what we can learn about galaxies in general from studying just a few galaxies in great detail (i.e. the Milky Way and its nearest neighbors). In particular, in this talk I will outline what current and future studies of the phase- and abundance-space distributions of stars in the Local Group might tell us about how galaxies form and evolve throughout the Universe.<br>