Abstract
The phase transition occurring at 25 K in , discovered almost 50 years ago, is the most long-lasting mystery in the physics of actinide compounds. Theories based on magnetic or electric-quadrupole order lead inevitably to fundamental, qualitative inconsistencies with observations. We show that the phenomenology of can be understood if the order parameter is assumed to be a magnetic octupole of ( ) symmetry. is the first compound for which indications of an octupolar phase transition have been found.
- Received 6 March 2000
DOI:https://doi.org/10.1103/PhysRevLett.85.2188
©2000 American Physical Society