Zero-field cooled specific heat of FeCl3 intercalated graphite

Specific heat measurements have been carried out down to below 0.5 K on a stage 5 sample that was cooled in zero magnetic field using a g-metal shield. In these measurements the specific heat anomaly is lowered to the temperature T similar to 0.8 K. Furthermore, the removal of the magnetic shield does not restore the higher temperature anomaly, even after the sample's temperature was raised above 10 K. The data also show a T-2 behavior above 1.4 K for the lattice component (theta(D) similar to 160 K), which is indicative of a 2D phonon spectrum. However, similar measurements on a stage 2 sample just reproduced the phase transition at similar to 1.8 K, while extending the temperature range allowing measurements of the electronic contribution to the specific heat.