Eur. Phys. J. B 45, 157-168 (2005)
https://doi.org/10.1140/epjb/e2005-00073-y

Epitaxial growth and magnetic exchange anisotropy in Fe₃O₄/NiO bilayers grown on MgO(001) and Al₂O₃(0001)

¹ CEMES-CNRS, 29 rue J. Marvig, BP 94347, 31055 Toulouse Cedex, France
² LNMO, 135 avenue de Rangueil, 31077 Toulouse Cedex 4, France

Corresponding author: ^a snoeck@cemes.fr

Received: 15 September 2004
Revised: 10 December 2004
Published online: 15 March 2005

Abstract

Epitaxial Fe₃O₄/NiO bilayers were epitaxially grown on MgO(001) and Al₂O₃(0001) substrates to investigate the influence of the fully spin compensated (001) and the non-compensated (111) NiO interface planes between the ferromagnetic (F) and antiferromagnetic (AF) layers on the AF/F exchange coupling. Bilayers of different magnetite thicknesses and constant NiO thickness were investigated. The structural characterizations indicate a perfect epitaxy of the two layers for the both growth directions in the two Fe₃O₄/NiO/MgO(001) and NiO/Fe₃O₄/Al₂O₃(0001) systems. An epitaxial ferrimagnetic (Ni,Fe)Fe₂O₄ phase is observed at the AF/F interface when the NiO oxide is grown on the top of the Fe₃O₄ layer while a perfectly flat AF/F interface is observed in the Fe₃O₄/NiO/MgO(001) system exhibiting only a very slight interdiffusion. Magnetic measurements indicate a relative strong bias at 300 K for the bilayers grown on Al₂O₃(0001), which decreases with the inverse of the ferrimagnetic layer thickness as theoretically expected. On the contrary, a zero exchange biasing is observed at 300 K for the bilayers grown on MgO(001).