The thickness, electric field, and strain effects on the magnetic anisotropy of FeCo/MgO(001) thin films: A first principles study

Abstract

The magnetic anisotropy of the FeCo/MgO(001) thin films with the effects of thickness, the electric field, and the strain of the in-plane lattice constant were investigated by first-principles calculations. The thickness dependence of the magnetic anisotropy of FeCo ultrathin films in the range of one to four monolayers was explored, and the films with one, three, and four FeCo monolayers preferred the in-plane easy axis of magnetization, while the film with two FeCo monolayers occupied the perpendicular anisotropy. In the presence of an electric field, the magnetic anisotropy energies for all four films could be enhanced; moreover, the transition of the easy axis of magnetization from in-plane to out-of-plane also could be obtained, and the transition electric field was related with their thickness. It could be found that the variation of the in-plane lattice constant resulted in the switching from the perpendicular to in-plane anisotropy for the film with two FeCo monolayers.

Field angle dependence of voltage-induced ferromagnetic resonance under DC bias voltage

“…Much research has been carried out to understand and improve the properties of this voltage effect [3][4][5][6][7][8][9][10]. The mechanism can be understood as a charge accumulation/subtraction or shift of band filling at the metal/dielectric interface as a result of the application of voltage [11][12][13][14][15]. One useful technology that exploits this effect is the voltage-induced ferromagnetic resonance (FMR) technique in magnetic tunnel junctions (MTJ) [16,17], which utilizes it for microwave detection.…”

Quantifying perpendicular magnetic anisotropy at the Fe-MgO(001) interface

“…[8][9][10][11][12] Theoretical analyses highlight different possible mechanism that would lead to PMA and generally involves band hybridization, spin-orbit coupling splitting or strain. [13][14][15] Particularly, Yang et al attributed the PMA to a combination of two factors: overlap between O-pz and transition metal dz 2 orbitals, as well as degeneracy lift of out-of-plane 3d orbitals induced by spinorbit coupling. 14 In addition, He and Chen have shown that the lattice mismatch between MgO and FeCo could also induce an additional PMA.…”

Strain control magnetocrystalline anisotropy of Ta/FeCo/MgO heterostructures

“…Interestingly, the magnetization of the system is switched from perpendicular at g FeCo ¼ 2% to in-plane orientation at g FeCo ¼ 4%. Such a strain-induced variation and magnetic switching have also been predicted in a similar model of the Ta/FeCo/MgO heterostructure by He and Chen, 23 in which the FeCo layer is not of B2-type, but in L6 0 structure with Fe and Co present on the same atomic plane.…”