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Self-assembled bilayer molecular metals (CNB-EDT-TTF)4X;The role of C-N•••H interactions in a new prototype of 2D Molecular Conductors
Date : Wednesday, October 18th, 2017 15:00 - 16:00 Place : Seminar Room 5 (A615), 6th Floor, ISSP Lecturer : Prof. Manuel Almeida Affiliation : Instituto Superior Técnico, University of Lisbon Committee Chair : Hatsumi MORI (63444)

The electron donor BEDT-TTF and related symmetrical derivatives have been at the origin of a large number of 2D electronic systems presenting a large diversity of ground states that have been intensively studied during the last years.
In this presentation it will be shown how dissymmetrical ET derivatives like cyanobenzene-ethylenedithio-tetrathiafulvalene (CNB-EDT-TTF), thanks to a combination of C-NH hydrogen bond assisted dimeric interactions can be at the origin of a new type of 2D systems, (CNB-EDT-TTF)4X, (X= ClO4, PF6, I3, …) which are characterized by a unique bilayer structure of the donors.
This novel type of salts exhibit 2D metallic properties with special characteristics derived both from the unusual stoichiometry and the weak interaction between paired layers. These properties are related to a high band filling, large electronic effective masses and quasi degenerated 2D Fermi surfaces, as predicted by band structure calculations and in agreement with electron transport measurements in single crystals. Depending on the donor packing pattern some of these 2D metals can present superconductivity at temperatures close to 3K.
The formation of the bilayers by self-assembly is however critically dependent on the counter anions and growth conditions. The rich variety of polymorphism and physical properties that has been recently observed in these (CNB-EDT-TTF)4X salts will be also presented in detail.

(Published on: Tuesday October 10th, 2017)