Superconducting properties of. beta. -(BEDT-TTF)/sub 2/I/sub 3/ crystals

The temperature dependence and anisotropy of the critical magnetic field in an organic superconductor ..beta..-(BEDT-TTF)/sub 2/I/sub 3/ are measured. The value of H/sub c/2 when H-barparallela-bar is approximately equal to the value of H/sub c/2 when H-barparallelb-bar and exceeds H/sub c/2 by almost an order of magnitude when H-barparallelc-bar. The state density is estimated to be N(0)approx. =0.25 x 10/sup 34/ erg/sup -1/xcm/sup -3/. The critical temperature of the superconducting transition increases from 1.3 K to 4.5 K as a result of thermal cycling from liquid-helium temperature to room temperature. The sample goes superconducting at Tapprox. =7 K.