MAGNETIC-ORDERING IN CERIUM MONOCHALCOGENIDES - TEST CASE FOR EPSILON-EXPANSIONS WITH N=4

CeSe and CeTe are found by neutron diffraction to be type-II antiferromagnets with the moment along the propagation vector. The phase transitions are continuous with the critical exponent for the magnetization β=0.36±0.02. This constitutes a violation of the ε-expansion predictions of Bak, Krinsky, and Mukamel, which hitherto have been successfully applied to a number of n>~4 systems and according to which the transitions should be of first order. © 1979 The American Physical Society.