https://doi.org/10.1140/epjb/e2005-00181-8
Structural and magnetic properties of ion-beam deposited NiFe/Co-oxide bilayers
Department of Materials Engineering, National Chung Hsing University,
Taichung 402, Taiwan, R.O.C.
Corresponding author: a kwlin@dragon.nchu.edu.tw
Received:
15
September
2004
Revised:
18
May
2005
Published online:
28
June
2005
The structural and magnetic properties of NiFe/Co-oxide bilayers were
studied. XRD investigation indicates the NiFe (Permalloy) layers (a= 3.53
Å) grow with a (111) preferred orientation. The Co-oxide layers were
fabricated with oxygen content in the deposition assist beam ranging from
8% (rock-salt CoO, a= 4.27 Å) to 34% (spinel Co3O4, a=
8.21 Å). Both the coercivity Hc and exchange bias field Hex
closely follow an inverse NiFe thickness relationship. A strong temperature
dependence of Hc and Hex is found in these NiFe/Co-oxide bilayers.
At T= 289 K, the NiFe/CoO film exhibits an enhanced Hc relative to pure
NiFe/Co or NiFe/Co3O4 bilayers, an indication of exchange coupling
between the NiFe and CoO phases. At T= 10 K, the NiFe/Co3O4 film
exhibits an exchange-bias loop shift of Oe that
persists to temperatures greater than 30 K (the Néel temperature of bulk
Co3O4). The transition temperature of the Co3O4 film
component has increased above the bulk value via exchange coupling with the
permalloy. Results indicate that the exchange coupling interaction between
FM and AFM layers are responsible for both enhanced coercivity and cross-tie
domains.
PACS: 75.70.Cn – Magnetic properties of interfaces (multilayers, superlattices, heterostructures)
© EDP Sciences, Società Italiana di Fisica, Springer-Verlag, 2005