Collapse of the magnetic hyperfine field by intense rf perturbation

By carrying the technique of rf enhancement to its extreme limit, the entire magnetic hyperfine field at an iron nucleus was made to oscillate rapidly through large angles in response to an applied rf field. When the frequency of these rf oscillations was increased to several times the nuclear Larmor frequency, the time average field seen by the iron nuclei was reduced from ∼300 kG to zero.