Dresden 2011 – scientific programme

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HL: Fachverband Halbleiterphysik

HL 5: Innovative Systems and Devices

HL 5.2: Talk

Monday, March 14, 2011, 10:30–10:45, POT 06

Disorder induced localization in crystalline phase-change materials — •Peter Jost¹, Theo Siegrist^1,2, Hanno Volker¹, Michael Woda¹, Philipp Merkelbach¹, Carl Schlockermann¹, and Matthias Wuttig¹ — ¹I. Physikalisches Institut (IA), RWTH Aachen University, 52056 Aachen, Germany — ²Department of Chemical and Biomedical Engineering, Florida State University, Tallahassee, FL 32310

Phase-change materials (PCMs) are ideally suited for data storage devices employing the amorphous to crystalline phase transition. In this work[1] we report on a metal insulator transition (MIT) in the crystalline state of the pseudo-binary alloys between GeTe and Sb₂ Te₃. The insulating state results from a degree of disorder which is untypically high for crystalline solids. The change of disorder upon annealing leads to the MIT. Moreover, we will demonstrate that this MIT is accompanied by a universal minimum metallic conductivity for all alloys under investigation. While MITs have been discussed as consequences of disorder induced localization (Anderson) and electron correlation effects (Mott) at the same time, the latter (Mott type) is often dominant. We will, however, show that disorder induced localization must be prevalent here. Thus, the crystalline phase of PCMs constitutes a very uncommon state of matter being equally interesting for technical applications and fundamental research on localization physics.

[1] Siegrist, T. et al. Accepted for publication in Nature Mater.