Hard X-ray photoemission study of the Fabre salts (TMTTF)(2)X (X = SbF6 and PF6)

Author(s):Show less -

Medjanik, Katerina ^[1] ; de Souza, Mariano ^[2] ; Kutnyakhov, Dmytro ^[1] ; Gloskovskii, Andrei ^[3] ; Mueller, Jens ^[4] ; Lang, Michael ^[4] ; Pouget, Jean-Paul ^[5] ; Foury-Leylekian, Pascale ^[5] ; Moradpour, Alec ^[5] ; Elmers, Hans-Joachim ^[1] ; Schoenhense, Gerd ^[1]

Affiliation

^[1] Johannes Gutenberg Univ Mainz, Inst Phys, D-55099 Mainz - Germany

^[2] Unesp Univ Estadual Paulista, Dept Fis, IGCE, BR-13506900 Rio Claro, SP - Brazil

^[3] Deutsch Elektronen Synchrotron DESY, D-22607 Hamburg - Germany

^[4] Goethe Univ Frankfurt, Phys Inst, D-60438 Frankfurt - Germany

^[5] Univ Paris 11, Lab Phys Solides, CNRS UMR 8502, F-91405 Orsay - France

• Document type: Journal article
• Source: European Physical Journal B; v. 87, n. 11 NOV 3 2014.
• Web of Science Citations: 12

Abstract

Core-level photoemission spectra of the Fabre salts with X = SbF6 and PF6 were taken using hard X-rays from PETRA III, Hamburg. In these salts TMTTF layers show a significant stack dimerization with a charge transfer of 1e per dimer to the anion SbF6 or PF6. At room temperature and slightly below the core-level spectra exhibit single lines, characteristic for a well-screened metallic state. At reduced temperatures progressive charge localization sets in, followed by a 2nd order phase transition into a charge-ordered ground state. In both salts groups of new core-level signals occur, shifted towards lower kinetic energies. This is indicative of a reduced transverse-conductivity across the anion layers, visible as layer-dependent charge depletion for both samples. The surface potential was traced via shifts of core-level signals of an adsorbate. A well-defined potential could be established by a conducting cap layer of 5 nm aluminum which appears ``transparent{''} due to the large probing depth of HAXPES (8-10 nm). At the transition into the charge-ordered phase the fluorine 1s line of (TMTTF)(2)SbF6 shifts by 2.8 eV to higher binding energy. This is a spectroscopic fingerprint of the loss of inversion symmetry accompanied by a cooperative shift of the SbF6 anions towards the more positively charged TMTTF donors. This shift does not occur for the X = PF6 compound, most likely due to smaller charge disproportion or due to the presence of charge disorder. (AU)

• FAPESP's process: 11/22050-4 - Exploring thermodynamic and transport properties of strongly correlated electron systems
• Grantee: Valdeci Pereira Mariano de Souza
• Support Opportunities: Regular Research Grants