Physical properties of (TMET-STF)2BF4

Organic superconductor (TMET-STF)2BF4 (Tc=4.1K) exhibits resistivity anomalies around 13K and 100K. In order to clarify the electronic state, we performed the optical and transport measurement. The reflectance spectra are well explained by the molecular orbital calculations. The interlayer resistance below 100K depends on the cooling rate around 100K. In the superconducting state under slow cooling process, the interlayer coherence length is comparative with the interlayer distance, leading to two-dimensional character of the superconducting state.