Critical behavior study of the spin ordering transition in RVO3 (R = Ce, Pr, Nd, Sm, Gd, Er) by means of ac photopyroelectric calorimetry

The thermal diffusivity of RVO3 single crystals (R = Ce, Pr, Nd, Sm, Gd, and Er) has been measured with an ac photopyroelectric calorimetry in the region in which the G-type orbital ordering and C-type spin ordering take place. Detailed measurements in the close neighbourhood of the spin ordering temperature have allowed to extract the critical parameter α and the critical ratio A+/A− for this transition. While the samples containing Ce, Nd, Sm and Er belong to the 3D-XY universality class (showing that the spins have an easy plane anisotropy), the sample with Gd, which is known to present a clear easy axis, belongs to the 3D-Ising class. Finally, PrVO3 shows an effective isotropic behavior, as the critical parameters found agree with the 3D-Heisenberg class.