Novel Low Temperature Modulated Structure of the Ambient Pressure Superconductor (BEDT-TTF)₂I₃ and a Design Strategy for New Superconducting Polyhalide Phases

Abstract

Abstract The first ambient pressure S-based organic superconductor (BEDT-TTF)2I3, abbreviated (ET)2I3, exhibits a novel modulated structure below ∼ 200 K. At 125 K the ET molecules and I3 − anions exhibit large displacements 0.124 (3) A and 0.281 (1) A, respectively, from their positions in the “average structure.” New ambient pressure superconducting polyhalide derivatives such as (ET)2IBr2 are discussed with transition temperatures of 2.7 K, and in one sample, 4.2 K.