Competition between Ferrimagnetism and Magnetic Frustration in Zinc Substituted YBaFe₄O₇

The substitution of zinc for iron in YBaFe 4 O 7 has allowed the oxide series YBaFe 4− x Zn x O 7, with 0.40 ≤ x ≤ 1.50, belonging to the “114” structural family to be synthesized. These oxides crystallize in the hexagonal symmetry ( P 6 3 mc ), as opposed to the cubic symmetry (F -43 m ) of YBaFe 4 O 7 . Importantly, the dc magnetization shows that the zinc substitution induces ferrimagnetism, in contrast to the spin glass behavior of YBaFe 4 O 7 . Moreover, ac susceptibility measurements demonstrate that concomitantly these oxides exhibit a spin glass or a cluster glass behavior, which increases at the expense of ferrimagnetism, as the zinc content is increased. This competition between ferrimagnetism and magnetic frustration is interpreted in terms of lifting of the geometric frustration, inducing the magnetic ordering, and of cationic disordering, which favors the glassy state.