Pf. Henning et al., THERMODYNAMIC EVIDENCE FOR A LOW-TEMPERATURE PHASE-TRANSITION IN THE ORGANIC CONDUCTOR ALPHA-(BEDT-TTF)(2)MHG(SCN)(4)(FOR M=K,RB), Solid state communications, 95(10), 1995, pp. 691-694
We have measured the ac heat capacity of the organic conductor alpha-(
BEDT-TTF)(2)MHg(SCN)(4) (for M = K, Rb) via a low addenda optically he
ated calorimetric method. We find, contrary to previous reports, a ris
e Delta C in the heat capacity near a transition temperature T-DW. The
BCS parameter Delta C/gamma T-c for the transitions ranges from 7.5 t
o 0.1 depending on different estimates of the electronic density of st
ates. Nevertheless, the results are consistent with the opening of a d
ensity wave gap at T-DW in the open orbit band, and a reconstruction o
f the closed orbit band at lower temperatures.