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TT: Fachverband Tiefe Temperaturen

TT 21: Solids at Low Temperature - Poster Session

TT 21.19: Poster

Mittwoch, 28. März 2007, 14:00–17:45, Poster A

Soft phonon modes in phase change materials — •Dominic Lencer¹, Blazej Grabowski², Jörg Neugebauer², and Matthias Wuttig¹ — ¹I. Physikalisches Institut (1A), RWTH Aachen, D-52056 Aachen — ²Max-Planck-Institut für Eisenforschung, Max-Planck-Straße 1, D-40237 Düsseldorf

Among the candidates for non-volatile memories succeding Flash phase change RAM (PCRAM) is attracting much interest from basic and industrial research groups. It is based on reversible electrically induced switching of small cells between an amorphous and crystalline state.

In general, the employed metastable crystalline phases of alloys used for PCRAM devices resemble slightly distorted cubic structures. In order to investigate the particular distortions, phonon dispersions were calculated for the symmetric cubic phases of GeTe, Sb₂Te₃ and GeSb₂Te₄ using density functional calculations using both the linear response and a direct method. Soft phonon modes were identified and sampled to yield models for the distorted phases. Properties of both undistorted and distorted phases are presented and compared to experimental data.