Speaker: Richard James (University of Minnesota)

Room: SISSA - Santorio A - room 136

Abstract: 
We present some recent examples of new materials whose synthesis was guided by some essentially mathematical ideas. They are materials that undergo phase transformations from one crystal structure to another, with a change of shape but without diffusion.  They are hard materials, but nevertheless show liquid-like changes of microstructure under a fraction of a degree change of temperature.  The underlying mathematical theory was designed to identify alloys that show low hysteresis and exceptional reversibility. The new alloys, of which Zn45Au30Cu25 is the best example so far, do show unprecedented levels of these properties, but also raise fundamental questions for theory. Some of these alloys have a strongly magnetic phase and a nonmagnetic phase. These can be used to convert heat to electricity (without the need of a separate electrical generator), and provide interesting possible ways to recover the vast amounts of energy stored on earth at small temperature difference.