Regensburg 2013 – wissenschaftliches Programm

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O: Fachverband Oberflächenphysik

O 58: Poster Session III (Solid-liquid interfaces; Scanning probe and other methods; Electronic structure theory; Spin-orbit interaction)

O 58.18: Poster

Mittwoch, 13. März 2013, 18:15–21:45, Poster B1

Characterization of single crystalline phase change materials by angular-resolved photoemission spectroscopy: Evidence for topological band inversion — •Christian Pauly¹, Marcus Liebmann¹, Alessandro Giussani², Jens Kellner¹, Sven Just¹, Jaime Sánchez-Barriga³, Andrei Varykhalov³, Oliver Rader³, Raffaella Calarco², and Markus Morgenstern¹ — ¹II. Phys. Institut B, RWTH Aachen University and Jara Fit, Germany — ²Paul Drude Institut für Festkörpelektronik, Berlin, Germany — ³Helmholtz-Zentrum für Materialien und Energie, Berlin, Germany

Phase change materials based on Ge-Sb-Te ternary alloys have been widely used as optical rewritable data storage media. They are also regarded as a promising candidate for a nonvolatile storage system (PCRAM), which exploits the high electrical contrast between the amorphous and the crystalline phase. Using angular-resolved photoemission spectroscopy (ARPES) we probe the band structure of epitaxially grown single crystalline phase change materials, Ge₂Sb₂Te₅ and GeTe. The samples are either transferred in-situ using a home-made UHV shuttle or cleaned by dipping in de-ionized water for 1min and annealing to 250^∘C in UHV [1]. ARPES maps show well defined bands for both materials. Interestingly, the band structure of Ge₂Sb₂Te₅ reveals a prominent bulk valence band which crosses E_F, forming two maxima around the Γ-point. According to recent DFT calculations [2], this is a hint for a spin-orbit induced band inversion which is a requirement for topological properties. [1] Z. Zhang et al., Appl. Surf. Sci. 256, 7696 (2010) [2] J. Kim et al., Phys. Rev. B 82, 201312 (2010)