OBSERVATION OF AN ORGANIC SUPERCONDUCTOR [BIS(ETHYLENEDITHIO)-TETRATHIAFULVALENE]2[CU(NCS)2] BY SCANNING TUNNELING MICROSCOPY

The surface of an organic high-Tc superconductor, (BEDT-TTF)2[Cu(NCS)2] [BEDT-TTF bis(ethylenedithio)tetrathiafulvalene, Tc= 10.4 K under ambient pressure], was observed with a scanning tunneling microscope in air and at room temperature. The step height observed on its surface was 13.2 A and was very close to the one layer thickness of the (BEDT-TTF)2 [cu(ncs)2] crystal (15.22 A, determined by x-ray diffraction). Periodic zig-zag structures were observed along the diagonal line of the surface unit cell and agreed well with the two-dimensional BEDT-TFF molecular structure projected onto its crystal b-c plane. © 1990, American Vacuum Society. All rights reserved.