First-principles investigation of the very large perpendicular magnetic anisotropy at Fe|MgO and Co|MgO interfaces

Abstract

The perpendicular magnetic anisotropy (PMA) arising at the interface between ferromagnetic transition metals and metallic oxides was investigated via first-principles calculations. In this work very large values of PMA, up to 3 erg/cm 2 , at Fe|MgO interfaces are reported, in agreement with recent experiments. The origin of PMA is attributed to overlap between O-p z and transition metal d z 2 orbitals hybridized with d xz(yz) orbitals with stronger spin-orbit coupling-induced splitting around the Fermi level for perpendicular magnetization orientation. Furthermore, it is shown that the PMA value weakens in the case of over-or underoxidation due to the fact that oxygen p z and transition metal d z 2 orbital overlap is strongly affected by disorder, in agreement with experimental observations in magnetic tunnel junctions.

Spin injection at remanence into III-V spin light-emitting diodes using (Co/Pt) ferromagnetic injectors

“…However, at this stage, one cannot totally discard the idea that the corresponding perpendicular magnetic anisotropy arises, in part, from the contribution of an out-of-plane pure interfacial anisotropy between epitaxial MgO and Fe layers as argued by Yang et al in a recent paper. 79 Nevertheless, the relatively low value (7%) of the EL circular polarization measured compared to the spin polarization of Fe (about 40%) can be understood as coming from a certain discontinuity of the Fe layer on MgO owing to nonperfect epitaxial growth, leading to paramagnetic islands. This is supported by the decrease of the polarized EL signal which disappears over 70 K (not shown).…”

Extremely large perpendicular magnetic anisotropy of an Fe(001) surface capped by5dtransition metal monolayers: A density functional study

“…A few theoretical groups also addressed Fe/MgO and FeCo/MgO interfaces and have argued that the PMCA of the Fe(001) film is enhanced by the hybridization of Fe 3d orbitals with O p z . 6,7 Nevertheless, recent experiments on TMs/FeCoB/MgO revealed evidence that the role of 5d or 4d orbitals is more decisive; in other words, that the 5d (4d) TMs/CoFeB interface is the origin of the observed PMCA. 8,9 On the other hand, the magnetism in multilayers of 4d and 5d TMs grown on body-centered cubic (bcc) Fe substrate has been a long-standing subject of both experiment [10][11][12][13][14][15] and theory.…”

Interface induced out-of-plane magnetic anisotropy in magnetoelectric BiFeO3-BaTiO3 superlattices

“…Moreover, it was also shown that in the case of a non-perfect interface (over-or underoxidized), the PMA amplitude is decreasing. 26 This is due to the disappearance of the d z 2 hybridized states around the Fermi level in the presence or absence of an additional oxygen atom at the interface.…”

“…27 These interfaces contain a number of imperfections including oxygen defects, which according to Yang et al, 26 weaken the out-of-plane magnetic anisotropy. When more layers are added, the subsequent interfaces show perfect atomic arrangement with sharp atomic interfaces.…”

“…Recently, interface PMA has been reported in metal/oxide systems like CoFeB-MgO 14 and Fe/MgO 24,25 The enhancement of the out-of-plane magnetic moment component in Fe/MgO was explained by the anisotropic orbital magnetic moments induced by the spin-orbit interaction at the interface. 24 Based on ab initio calculations, Yang et al 26 ascribed the large PMA at Fe/MgO interfaces and O-2p z orbitals at the interface. Moreover, it was also shown that in the case of a non-perfect interface (over-or underoxidized), the PMA amplitude is decreasing.…”