Heat Capacity Measurement of
Cu Complex under High Pressure,
Low Temperature, and Magnetic Field
— Searching for Pressure-Induced Ferromagnetic Phase —

We measured heat capacities of Cu complex, Cu2(OH)3(CH3CO2)⋅H2O, under several pressures and magnetic fields. This compound shows antiferromagnetic transition below 12 K under ambient pressure and pressure-induced ferromagnetic transition under 1.2 GPa. We detected distinct anomalies of the antiferromagnetic transition at 2.2 K and 4.5 K under ambient pressure which is also confirmed by relaxation method. Ferromagnetic character of the transition is gradually enhanced with applying pressure up to 1.4 GPa but decreased with applying further pressure. We understand that these complicated magnetic features come from complicate relation of exchange interactions in copper hydroxide layer of Cu2(OH)3(CH3CO2)⋅H2O.

(by Y. Muraoka & Y. Nakazawa)

Fig. 1. Temperature dependence of heat capacity of Cu2(OH)3(CH3CO2)⋅H2O under ambient pressure obtained under 0, 0.1, 0.5 , 1, 3, and 7 T. Sample is coated by Stycast 1266 (a) and Stycast 2850FT (b), respectively.

Fig. 2. Temperature dependence of ΔCp of Cu2(OH)3(CH3CO2)⋅H2O obtained under 0, 0.1, 0.5, 1, and 3 T under ambient pressure (a) and 1.4 GPa (b). ΔCp is defined as Cp(H) − Cp(7 T).