Ambient-pressure molecular superconductor with a superlattice containing layers of tris(oxalato)rhodate enantiomers and 18-crown-6

Abstract

We report a novel multilayered organic-inorganic hybrid material, β″-(BEDT-TTF)₂[(H₂O)(NH₄)₂Rh(C₂O₄)₃]·18-crown-6. This is the first molecular superconductor to have a superlattice with layers of both BEDT-TTF and 18-crown-6 and also the first with the anion tris(oxalato)rhodate. This is the 2D superconductor with the widest gap between conducting layers, where only a single donor packing motif is observed (β″). The strong 2D nature of this system strongly suggests that the superconducting transition is a Kosterlitz-Thouless transition. A superconducting T_c of 2.7 K at ambient pressure was found by transport measurements and 2.5 K by magnetic susceptibility measurements.