Using Landau-Ginzburg-Wilson Hamiltonians and renormalization-group arguments, it is shown that ${\beta }_{\alpha }$, the exponent characterizing the critical behavior of magnetoelectric susceptibility tensor elements in the region immediately below the antiferromagnetic ordering temperature, is equal to $\beta$, the critical exponent of the staggered magnetization.

• Received 8 September 1977

DOI:https://doi.org/10.1103/PhysRevB.17.297