Critical Behaviour of the Order Parameter From Birefringence and Raman Intensity Data Close to the λ-Transition In NH4Br
نویسنده
چکیده
The critical behaviour of the order parameter is investigated using the birefringence and Raman intensity data near the λ-phase transition (Tλ=235 K) in NH4Br. From the analysis of the experimental data using the mean field theory, the critical exponent for the order parameter is determined as β ≈ 0.5. This indicates a second order transition between the phases II (CsCl) and III (tetragonal) in NH4Br, as expected.Our results show that the mean field model is capable of describing the orderdisorder phase transition in the NH4Br crystal.
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تاریخ انتشار 2013