ESR study of a new phase of organic conductor (BEDT-TTF) 2I 3

Abstract

The anisotropic ESR linewidth, g value, line shape and spin susceptibility have been measured for the single crystal of BEDT-TTF cation salt, β' d-(BEDT-TTF) 2I 3, synthesized using diffusion method [1]. The measurements were performed over the temperature range from liquid nitrogen to the room temperature. A Lorentzian line shape was observed between the temperature range. The g values are independent of temperature when the static field is applied both parallel and perpendicular to the quasi-two-dimensional conducting plane (a-b plane). The spin susceptibility has a slight change at about 140K when the static field is applied parallel to a-b plane, while it is almost constant over the temperature range when the static field is applied perpendicular to a-b plane. The linewidth increases almost linearly with increasing temperature, and has a gradual change in slope around 140 K where a metal-semiconductor transition in resistivity measurement occurs.