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The Role of a Fragile-to-Strong Crossover in Crystallization of Glasses for Phase-Change Memory Application

Date: 2019-10-17
Time: 14:00
Venue: M253
Speaker: Dr. Jiri Orava

IFW Dresden, Institute for Complex Materials, Germany


In this talk, we will briefly introduce the characterization of crystallization mechanisms and dynamics in supercooled liquid: (i) by newly-emerging experimental techniques, allowing study of a wider temperature range of the existence of supercooled liquid, and measuring up to the maximum in the crystallization rate (mainly crystal-growth rate, U(T)) with high temporal resolution; and (ii) by computer simulations revealing the atomistic origin of crystallization and able to probe the early stages of nucleation processes which are difficult to access experimentally.

 We will show that the existence of a fragile-to-strong crossover in supercooled-liquid state is of fundamental interest and furthermore is of considerable practical importance. A fragile-to-strong crossover in the liquid phase of the chalcogenide forming the active layer of a phase-change memory device may help to improve the long-term stability (data retention) at temperatures somewhat above ambient, while permitting fast writing (i.e. crystallization) at high temperatures. The crossover thus can help to meet the contradictory needs for fast switching and good data retention in phase-change memory devices. We will also hint on the structural origin of such a crossover and relate its temperature dependence to the crystallization mechanism.

Brief CV of Dr. Jiri Orava:

Dr. Jiri Orava obtained his Ph.D. degree from the University of Pardubice, the Czech Republic in 2009. Since then, he has been working as a postdoctoral researcher at the University of Cambridge (UK), Tohoku University (Japan) and Leibniz Institute for Solid State and Materials Research Dresden (Germany). His research interests mainly include physical-chemical properties of metallic glasses, tailoring the relationship between structure and macroscopic properties of glasses, synthesis, physical-chemical properties of chalcogenide glasses, chalcogenide phase-change materials for non-volatile computer memory, crystallization and stability of glass-forming liquids, glasses and glass-ceramics for optics and photonics.