Nature of magnetic ordering in nanocomposites of Zn1-pNipO and NiO

Abstract A detailed study of the nature of magnetic exchange interactions and anisotropy in Zn 1− p Ni p O/NiO (0 ⩽ p ⩽ 1) two-phase nanocomposites is reported. The exchange constants | J 1 | and | J 2 | have been determined using the molecular field approximation for the two sublattice model which yields | J 2 | ∼ 11.26 meV and | J 1 | ∼ 7.17 meV for p  = 1, consistent with type-II antiferromagnetic ordering ( i.e. | J 2 |≫| J 1 |). A novel core-shell surface layer model has been employed to explain the nature of magnetic anisotropy in these nanocomposites which yields anisotropy constants K surface  = 2.42 erg/cm 2 , K bulk  = 2.61 × 10 6  erg/cm 3 and K shell  = 9.56 × 10 5  erg/cm 3 for shell thickness d sh ∼ 1.34 nm ( p  = 1).