Disordered mesoscopic systems:(a) Disordered nanostructures like quantum wires pose a challenge to the way we normally think of a macroscopic object. It is not enough to understand the `average' properties of various observables in such a system, because often the distributions are so broad that just the mean or the variance fails to provide any meaningful description of the system. Understanding various novel phenomena associated with such broad distributions in electronic transport properties as well as developing theoretical tools to describe their surprising universality is one of my main current interests. Recent works involve developing new methods to study quantum transport in three dimensions where there exists a transition between two limiting distributions of conductances, Gaussian in the metallic and close to log-normal in insulating regimes, with predictions of a novel intermediate distribution which is very broad and highly asymmetric.
(b) A second aspect involves understanding the statistical properties of energy levels in a system near the critical region of an Anderson transition from a metal to an insulator. Recent work involves understanding ``critical ensembles'' that contain multifractality of wave functions expected at the transition. Current research involves studying various properties of the q-random matrix ensembles and their relevance to physical systems.
(c) Another important focus is on electron transport in disordered ferromagnets. Understanding the temperature and disorder dependence of the longitudinal as well as the (anomalous) Hall conductivities i n thin feromagnetic films can in principle provide quantitative estimates of the spin dependent transport coefficients in magnetic materials. From a fundamental point of view, this will provide insights into the role of spin in transport phenomena. From a technological point of view, this could be important in the context of device technology based on spintronics. Recent work involves close collaboration with Prof. Art Hebard's group at UF, understanding the origins of the novel temperature and disorder dependence in thin Fe and Gd films.
Interplay of geometric frustration and long range order in molecular solids:This is a collaboration with N. Sullivan's experimental group studying the effects of geometrical frustration on orientational ordering in molecular solids. Recently the group (with J. Hamida and S. Pilla) has observed strong memory and aging effects in pure solid nitrogen, induced by a very small ac electric field in the audio frequency range. Current research involves understanding the origin of such effects and their consequences.
Recent collaborators: V. Gopar, J. Hamida, A. Hebard, M. Ismail, J. Klauder, P. Markos, P. Mitra, R. Misra, S. Pilla, N. Sullivan, P. W\"olfle.K. A. Muttalib / firstname.lastname@example.org / Last modified: Sept 14, 2007