Observation of a Very Large Internal Hyperfine Field (62.4 T) in the Ferromagnetically Ordered State of the <i>S</i> = 1 α-Iron(II) Octaethyltetraazaporphyrin

Abstract

The origins of the extraordinarily large internal hyperfine field (62.4 T) for the three-dimensional (weak) ferromagnetically ordered ground state of alpha-Fe(OETAP) are discussed semiquantitatively in terms of existing physical theory. In particular, the classical Fermi-contact contribution to the internal field is found to be highly enhanced by a very large orbital contribution and a significant dipolar term of the same sign. A rationale for the unexpected ordering of this S = 1 non-Kramers system is also presented.