Incommensurate structure and the superconducting properties of the organic superconductor (MDT-ST)(I3)0.417

The charge-transfer degree and the superconducting properties of the organic superconductor (MDT-ST)I 1+δ have been studied [MDT-ST: SH-2-(1,3-dithiol-2-ylidene)-1,3-diselena-4,6-dithiapentalene]. The Raman spectrum and the x-ray oscillation photograph show that the polyiodide chain is composed of I 3 +, which is incommensurate to the donor lattice. The chemical composition is determined to be (MDT-ST)(I 3 ) 0.417 . The upper critical fields are within the Clogston-Chandrasekhar paramagnetic limit in all directions, and the coherence lengths are longer than the thickness of the conducting sheet.