Determination of Band-filling Change in the Two-dimensional Organic Conductor, τ-(EDO-S,S-DMEDT-TTF)₂(AuBr₂)_1+y, (y≤0.875) by the Quantum Oscillation of Magnetoresistance

抄録

The effect of thermal treatment on the transport properties is studied for a two-dimensional organic conductor τ-(EDO-S,S-DMEDT-TTF)₂(AuBr₂)_1+y, (y≤0.875). The temperature dependence of the electric resistivity below room temperature was found to be changed from metallic down to low temperature to semiconducting by heating up to 420 K. One of the two frequencies of Shubnikov–de Haas oscillations are found to be different between the non-heated and heated parts from a single crystal, while no evidence of structural change in X-ray photograph was observed. The present result clearly shows that nominal valence or band filling can be controlled by simple thermal treatment for the quasi-two-dimensional organic metal. The mechanism of the change in the band filling is discussed in terms of anion decomposition.