Berlin 2012 – wissenschaftliches Programm

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TT: Fachverband Tiefe Temperaturen

TT 28: Correlated Electrons: Low-dimensional Systems - Materials 2

TT 28.8: Vortrag

Mittwoch, 28. März 2012, 17:00–17:15, H 0104

(TMTTF)₂SbF₆ at the Metal-Insulator Transition: Bulk-Sensitive Photoemission Facilitated by Aluminum Coating — Katerina Medjanik¹, Dmytro Kutnyakhov¹, Hans-Joachim Elmers¹, •Gerd Schönhense¹, Andrei Gloskovskii², Wolfgang Drube³, Mariano de Souza⁴, Jens Müller⁵, and Michael Lang⁵ — ¹Inst. f. Physik, Univ. Mainz — ²Inst. f. Anorg. und Anal. Chemie, Univ. Mainz — ³Deutsches Elektronen-Synchrotron, Hamburg — ⁴Universidade Estadual Paulista, Rio Claro, Brazil — ⁵Physikalisches Inst., Goethe Universität Frankfurt

The metal-insulator transition (MIT) in the title compound has been studied using hard X-ray photoelectron spectroscopy (HAXPES) at PETRA III (beamline P09). This material undergoes a transition from a correlated metal at ambient temperature to a Mott-Hubbard insulator at T=154 K. The latter is marked by a pronounced increase in resistivity by > 3 orders of magnitude and accompanied by a charge-order phase transition. Photoelectron spectroscopy for the bare material is hampered by strong non homogeneous surface charging visible by the sudden appearance of shifted lines in addition to the main line at the transition. The large information depth (about 20nm) of HAXPES allows coating the material by a thin (5 nm) conductive Al-layer in order to avoid charging. In this way, the intrinsic change of the spectra at the metal-insulator/charge-order transition can be observed. At the transition temperature, the S 2p signal exhibits a satellite shifted from the main line by 7.2 eV towards higher kinetic energies. Funded through Transregio SFB TR49, graduate school MAINZ and COMATT.