Effect of Orbital Hybridizations at the Interface on the Exchange Bias in SmFeO3/NiFe and SmFeO3/CoFeB Bilayers

In this work, the effect of orbital hybridizations at the interface on the exchange bias in SmFeO3/NiFe (3 nm) and SmFeO3/CoFeB (3 nm) bilayers prepared by pulsed laser deposition (PLD) combined with magnetron-sputtering technique on SrTiO3 (100) substrates was investigated. X-ray photoelectron spectroscopy (XPS) was employed to obtain the valence states of related elements in each layer and interface of the bilayer. With the purpose of studying the electronic structure of bilayers, especially the orbital hybridizations at the interface of bilayers, X-ray absorption spectroscopy (XAS) was also accomplished. Remarkably, the hybridizations of Co 3d - O 2p and Ni 3d - O 2p are confirmed in the SFO/CoFeB and SFO/NiFe bilayers, respectively. Meantime, it is observed that the bilayers exhibit different exchange bias effect (EB) from magnetization investigations, which are probably resulted from Co/Ni ions in oxidized states and the higher strength of hybridization of Ni 3d - O 2p than that of Co 3d - O 2p.