Controlled crystallization of superlattice reactants provides an additional synthetic route to these materials and increases the variety of compounds which can be intergrown. Researchers in Johnson's group characterize the materials they make in several ways. They measure physical properties such as magnetic susceptibility, electrical conductivity, electron spin resonance, thermal conductivity, Seebeck coefficients, superconducting critical temperatures - in short, anything that gives them information about the electrons in the system, both as magnetic moments and as charge carriers. Because many interactions are temperature-dependent and rather weak, they measure many of these properties as a function of temperature, typically from below 4.2K to room temperature or above. The results of the measurements are used to guide further synthetic efforts.
Researchers become experts in both synthesis and characterization of the new compounds they prepare.
The National Science Foundation , The Office of Naval Research , and the National Renewable Energy Laboratory . As a Function of Superlattice Structure. George S. Nolas, H. Takizawa, T. Endo.