The magnetic response of a ferrimagnetic/ferrimagnetic superlattice, [Fe3O4(20 Å/Mn3O4(80 Å)]x20, is measured as a function of external field (-50-50 kOe) and temperature (5-300 K). A compensation point (Tcp) is identified ∼33 K at which the remanence changes sign and low-field M-T curves show minima, indicating that the net moments of Fe3O4 and Mn3O4 are antiparallel. At temperatures >˜50 K, the magnetic response becomes pure Fe3O4-like. Detailed M-H curves (at T < 50 K) further exhibit magnetic phase transition at higher external field. As H is above H* ∼10kOe, the magnetization is enhanced and then saturates at H∼ 40 kOe. These phases are similar to the twisted phases, originating from a competition between Zeeman and exchange energies, previously observed in antiparallel metallic multilayers. A H-T magnetic phase diagram of the present superlattice is presented and five phases are included: the Mn3O4-aligned, Fe3O4-aligned, twisted, ferrimagnetic saturated, and pure Fe3O4 phases. M-H curves also show asymmetry at temperatures below and above Tcp, which is probably related to the anisotropy effect of Mn3O4(tetragonal structure). The fundamental mechanism of the antiparallel coupling between Mn3O4 and Fe3O4is also discussed.
|Journal||Physical Review B - Condensed Matter and Materials Physics|
|Publication status||Published - 2001 Feb 12|
All Science Journal Classification (ASJC) codes
- Electronic, Optical and Magnetic Materials
- Condensed Matter Physics