The magnetic orderings and phase transitions of rare-earth rhodium borides

Perturbation theory and mean-field approach have been employed in the present work to estimate the Heisenberg coupling constants J0ʹs for the ferromagnet DyRh4B4 and the antiferromagnet TmRh4B4 from their magnetic transition temperatures TMʹs in comparison with GdRh4B4. We found that the J0ʹs of these substances are different from each other, which may be attributed to their different electronic structures and also the anisotropic nature of the Heisenberg exchange coupling.