|Speaker :||Professor Sriram Shastry,
University of California Santa Cruz, CA 95064
|Topic :||Thermoelectric effects and new correlated materials|
|Date :||December 14, 2007|
|Time :||3:30 PM|
|Venue :||C V Raman Hall, IACS|
All are cordially invited to attend
Abstract: Thermoelectric effects and Correlated materials Abstract: Thermoelectricity is a foundational topic in statistical mechanics, dealing with reversible heat generation from a current flow. Kelvin established reciprocity using thermodynamic arguments in the nineteenth century. This is mysterious since transport is not within the domain of thermodynamics, and indeed Onsager later gave the correct framework during his seminal work on reciprocity. With regard to the Kelvin, I point out the origin of the mysterious "flaw in the ointment". Strangely enough, Kelvin's argument produces a fairly useful, if inexact estimator of thermopower in certain situations. After this historical footnote, I turn to the transition metal oxide Correlated materials, which are classical Mott Hubbard systems. Here the time honoured Bloch-Boltzmann equation approach meets a dead end, and must be discarded. (I display a cartoon based on the science fiction series Star Trek. A detailed knowledge of this series is helpful for understanding this part of the talk!). A new formalism, using dynamical heat response, enables a quantitative understanding of the sodium cobaltate materials. It also provides some new predictions for as yet unknown materials, with extremely large thermopower.