Abstract :

The study of the effects of disorder in electronic systems is an area of research that not only has a rich history but is also of deep contemporary relevance. In particular, these studies unraveled the very interesting phenomenon of Anderson localization wherein in low dimensions, all electronic states gets localized under the influence of arbitrarily small amount of impurities. This talk takes us on a guided tour of Anderson localization: Starting from the development of a phenomenological scaling theory, we will track the major mile-stones in the development of this field. As a way-point in our tour we will briefly discuss the extended classification scheme developed by Altland and Zirnbauer. This scheme classifies the disordered Hamiltonians in a ten-fold way on the basis of its underlying symmetries, thus completely specifying the low energy properties in each of these classes. Our tour culminates with a brief look at the low energy properties of graphene in the presence of vacancies (holes). We will show that graphene with vacancies is very unique and does not readily fall into the general classification scheme of Altland and Zirnbauer.

ABOUT THE SPEAKER:

Dr. Rajesh Narayanan obtained his Bachelors and Masters degree from the University of Mumbai. He earned his Ph. D (1999) from the University of Oregon working under the supervision of Prof. Dietrich Belitz. Subsequent to his Ph. D, he held post-doctoral positions at Oxford University (UK), Max-Planck Institute for Complex Systems, (Dresden, Germany), and the Institute of Nanotechnology at the Forschungszentrum Karlsruhe (Karlsruhe, Germany).
He joined the faculty of IIT-Madras in November 2006. He has also held visiting positions at Hong Kong University, Hong Kong University of Science and Technology, and Zhejiang University. His research interests lie in the field of quantum condensed matter systems. He is particularly interested in the influence of disorder on quantum phase transitions. In the recent past, he has also worked on dissipative systems like the spin-boson model, the Quantum hall effects, and DMFT based studies of the Mott-transition.