Zero field splitting

Zero field splitting describes various interactions of the energy levels of a molecule or ion resulting from the presence of more than one unpaired electron. The unpaired electrons mutually interact to give rise to two or more energy states. It is well known that degeneracy is lifted in the presence of a magnetic field, but zero field splitting occurs even in the absence of a magnetic field. ZFS is responsible for many effects in related to the magnetic properties of materials, as manifested in their electron spin resonance spectra and magnetism.