The specific heat in the normal and superconducting states of single-crystal intercalation compounds of the host material 2H-TaS 2 was measured from 1.7 to 9 K by use of a thermal relaxation method. By studying two extreme cases of charge transfer n, namely the 9 Å methylene blue intercalation compound (9 Å MB + -TaS 2 ) (n ) 0.06) and K 0.33 TaS 2 (n ) 0.33), and comparing the results with literature data, it is seen that charge transfer has only minor influence on the electronic specific heat in the normal state. This is in drastic contradiction to the expectation from a rigid band model. The contribution of the phonon-parameter β, however, varies with intercalation. No direct correspondence between T c and the Debye temperature θ D can be seen, but if θ D is multiplied by a factor, characterizing the intercalation compound, scaling between T c and the corrected Debye temperature θ D corr is found. Furthermore, it is observed that the superconducting transition temperature of the methylene blue intercalation compound is sensitive to cooling rate.

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