Magnetic phase transition of stage-1 ternary CoCl₂-FeCl₃-graphite intercalation compound

The stage-1 ternary CoCl₂-FeCl₃-graphite intercalation compound forms an ideal heterostructure with the stacking sequence . . . -C-CoCl₂-C-FeCl₃-C-CoCl₂-C-FeCl₃-C- . . ., where competition may occur between the CoCl₂ layer and the FeCl₃ layer for receiving a donated charge from the graphite layer. This compound undergoes two magnetic phase transitions at T_cl(=8.0K) and T_cu(=8.8K). The intermediate phase between T_cl and T_cu may be regarded as the two-dimensional (2D) XY phase slightly modified by the finite-size effect. The low-temperature phase below T_cl is the antiferromagnetic phase where the 2D ferromagnetic sheets are stacked along the c axis.