On the formation of structure and electronic transport

Abstract

By systematic studies of amorphous systems (and most of the results are transferable to liquid systems) we are able to show that structure formation at early stages is to a high degree the effect of self-organized and hence optimized resonances between macroscopic subsystems. There is, for example, a spherical-periodic resonance, based on momentum exchange between the valence electrons in total as one subsystem, and the forming static structure as the other one. It causes spherical structural periodicity of nearest-neighbour shells at medium distances and is a global effect, giving rise to similar effects as described by Bloch's theorem in crystals. Resonances based on an exchange of angular momentum became apparent too. Accordingly, together with the local quantum chemical effects, global resonances are important as well and both will cooperate to get the most optimal energetic situation for the total system. Occasionally, the global effects even dominate structure formation. We report on different scenarios where the total system is able to optimize the resonances. The resonance model explains major structural features of many liquid and amorphous systems of different types as there are pure elements, binary as well as ternary alloys, metallic glasses, glassy semiconductors, glassy Zintl systems, and light-weight Al–TM alloys (TM: from Ti to Cu). Spherical-periodic order causes pseudogaps or even gaps at the Fermi energy and hence has dramatic influences on any electronic transport. Accordingly, understanding structure formation on the basis of resonances also triggers a deeper understanding of electronic transport properties.