Antiparallel state, compensation point, and magnetic phase diagram ofFe3O4/Mn3O4superlattices

G. Chern, Lance Horng, W. K. Shieh, T. C. Wu
2001 Physical Review B (Condensed Matter)  
The magnetic response of a ferrimagnetic/ferrimagnetic superlattice, ͓Fe 3 O 4 (20 Å)/Mn 3 O 4 (80 Å)͔ x20 , is measured as a function of external field ͑Ϫ50-50 kOe͒ and temperature ͑5-300 K͒. A compensation point (T cp ) is identified ϳ33 K at which the remanence changes sign and low-field M-T curves show minima, indicating that the net moments of Fe 3 O 4 and Mn 3 O 4 are antiparallel. At temperatures Ͼϳ50 K, the magnetic response becomes pure Fe 3 O 4 -like. Detailed M-H curves ͑at TϽ50 K)
more » ... urves ͑at TϽ50 K) further exhibit magnetic phase transition at higher external field. As H is above H*ϳ10 kOe, the magnetization is enhanced and then saturates at H ϳ40 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 Mn 3 O 4 -aligned, Fe 3 O 4 -aligned, twisted, ferrimagnetic saturated, and pure Fe 3 O 4 phases. M-H curves also show asymmetry at temperatures below and above T cp , which is probably related to the anisotropy effect of Mn 3 O 4 ͑tetragonal structure͒. The fundamental mechanism of the antiparallel coupling between Mn 3 O 4 and Fe 3 O 4 is also discussed.
doi:10.1103/physrevb.63.094421 fatcat:dedbzob6nzcmni3maxk6garep4