Surface Study of an Organic Superconductor κ- (BEDT-TTF) 2Cu (NCS) 2 Using a Scanning Tunneling Microscope

The surface structure of κ- (BEDT-TTF) 2Cu (NCS) 2 [BEDT-TTF, his (ethylenedithio) tetrathia-fulvalene] crystal was studied by scanning tunneling microscopy (STM). The STM image over the crystal be plane has revealed the individual BEDT-TTF molecules, whose arrangement is in good agreement with the projected image of the bulk structure determined by X-ray diffraction. The alternative stacked structure of BEDT-TTF layer and Cu (NCS) 2 layer was also revealed by the measurement over the ab-plane.