Specific heat of organic superconductor λ-(BEDT-TSF)2GaCl4

We have measured the specific heat of λ-(BEDT-TSF)2GaCl4 by a thermal relaxation method below 7 K to study the superconducting state. The specific heat jump due to the superconducting transition at <F>Tc=4.8</F> K is observed. For the normal state, we have determined the electronic specific heat coefficient <F>γ=14.4±3.4</F> mJ/mol K2 and the Debye temperature of <F>ΘD=194.0±0.4</F> K. The discontinuity of the specific heat is evaluated to be <F>ΔC/γTc=1.37±0.32</F>, which coincides with a Bardeen–Cooper–Schrieffer (BCS) relation <F>ΔC/γTc=1.43</F> for a weak-coupling limit. The zero-crossing (<F>ΔC=0</F>) occurs at 0.67Tc, which has been similarly observed in BEDT-TTF-based superconductors. [Copyright &y& Elsevier]