Photopyroelectric study of the thermal parameters of antiferromagnets at the Neel temperature

High resolution measurements have been performed with the photopyroelectric technique to study the static and dynamic critical behaviour of the thermal parameters of the two antiferromagnets Cr2O3 and FeF2 close to the Neel temperature. Specific heat, thermal diffusivity and thermal conductivity behaviours have been simultaneously measured in the critical region of the second order antiferromagnetic-paramagnetic phase transition. Critical exponents and the critical amplitude ratios of specific heat and thermal diffusivity have been determined. We have also studied single crystal Chromium for which the antiferromagnetic - paramagnetic phase transition is first order. The effect of thermal annealing on the signal amplitude and phase in the vicinity of the transition has been reported.