Phase transition and critical behaviors of spin-orbital coupling spinel compound CdV2O4.

The temperature dependent susceptibility and specific heat of spinel compound CdV2O4 were investigated. The structural transition accompanied with orbital order appearing at 89.6K is confirmed to be a first order transition, while the magnetic transitions at 30.2K is revealed to be a second order one. For the paramagnetism-antiferromagnetic transition, the width of critical region was estimated to be about 1.5K by differentiating with Gaussian fluctuation. In critical region, the critical behavior of specific heat was compared with renormalization-group theory. Critical exponent α and critical amplitude ratio (A+/A–) fitting to the data was found to be –0.017 and 1.26, respectively. The value of A+/A– shows the critical behavior of CdV2O4's deviates from 3D-Heisenberg and shifts to 3D-XY. The analysis of specific heat in low temperature range gives out that Debye temperature ϴD for CdV2O4 is estimated to be 190 K. [ABSTRACT FROM AUTHOR]