Studies of heteroepitaxial growth of Fe/MgO/Fe3O4 multilayer on MgO (100) substrates for fabrication of magnetic tunnel junctions

Epitaxial Growth of half-metallic oxide thin Films by Pulsed Laser Depositions.

“…5 As can be seen from the fit, the RMS roughness is relatively low, ∼ 0.2 nm, this being indispensable for the patterning of micrometric MTJs. The obtained values are smaller than those reported in MBE-deposited samples [262], but probably due to the larger roughness of the commercial MgO substrate utilized in that work and/or different growth mechanisms. In our study, we have found no clear correlation between the interface roughness and the temperature growth of the different layers.…”

“…In addition, interest in spintronic structures based on magnetic oxides has increased recently [259], and MgO is a serious candidate as tunnel barrier because of the small lattice mismatch with the Fe 3 O 4 (0.3%) electrode [260][261][262]. Nevertheless, the performance of Fe 3 O 4 -based MTJs has been limited with scattered values and a maximum of 14% MR at room temperature [263][264][265], and other than MgO tunnel barriers were not significantly better [266][267][268][269][270].…”

“…A 2-nm-thick passivation layer on the Fe surface (labeled as FeO x ) due to the exposure to ambient atmosphere is observed. The interface roughness and roughness correlation between interfaces in tunnel devices are thought to be critical for their spin-transport properties [262]. XRR in a selected heterostructure where both MgO barrier and Fe counterelectrode have been deposited at RT is shown in Fig.…”

Anisotropic transport behavior in ultrathin epitaxial Fe films on vicinal oxide substrates

“…The MgO substrates were annealed in situ in an oxygen and oxygen plasma environment prior to deposition. 6 A 25-nm MgO cap layer was deposited on top of the Fe film to prevent oxidation. The substrate temperature during Fe deposition was 200°C and the deposition rate was 0.1 Å / s. In situ reflection high-energy electron diffraction ͑RHEED͒ was employed to monitor the growth of the films.…”

Link between local iron coordination, Fe 2p XPS core level line shape and Mg segregation into thin magnetite films grown on MgO(001)

“…Mg interdiffusion [17][18][19] and the formation of an MgO rich interface layer have been reported [20][21][22] . MgO segregation across the MgO/Fe 3 O 4 interface is crucial since the influence of grain boundaries, interface roughness and in particular anti phase boundaries, which might partly stem from Mg segregation into the Fe 3 O 4 layer, on the lowfield magneto resistance response is at least partly controversial [23][24][25][26][27][28] . In particular, Kalev et al find the Fe ions at the Fe 3 O 4 /MgO interface to be in the Fe 3+ valence state 30 , leading to a significant reduction of spin fluctuations and magnetic neighbors at the interface.…”