Specific Heat of the Magnetic Chain TMMC Below 1.2 K

Specific heat measurements are reported for single crystal (CH3)4NMnCl3 (TMMC) from 0.55 to 1.2 K in zero applied magnetic field. A peak in the magnetic contribution to the specific heat was found at 0.850 ± 0.005 K which could be attributed to a 1d to 3d transition. The peak height was 360 mJ/mole‐K. The ratio of the interchain to intrachain exchange constants is estimated to be 8 × 10−5 via a Green's function calculation using a Neel temperature of 0.85 K and a intrachain exchange constant of 6.6 K.