The growth and magnetic anisotropy of bulk and epitaxial tetragonal CuFe204+

Abstract
For copper ferrite to assume the tetragonal phase it is necessary that more than a certain fraction of the spinel octahedral sites be occupied by Cu 2+ ions. To exceed this critical occupation, copper ferrite must be nearly stoichiometric. We have established that there is a systematic relationship between copper deficiency in (Bi203/B203) flux‐grown copper ferrite and the growth temperature. In particular it is necessary to grow at low temperatures (<800°C) to obtain stoichiometric CuFe204. We have grown bulk single crystals and epitaxial films (on spinel substrates) from a stable melt at about 795°C. The bulk crystals evidence a microtwinning habit. Annealed epitaxial layers of CuFe204 display a uniaxial magnetic anisotropy with easy axis perpendicular to the films. The anisotropy is sufficiently strong (Ku?6.0×105ergs/cc) to overcome the demagnetizing effects of the thin films, suggesting that CuFe204 may have application as a bubble domain material.