CoFeB/MgO/CoFeB structures with orthogonal easy axes: perpendicular anisotropy and damping

Abstract

We report on the Gilbert damping parameter $\alpha$, the effective magnetization $4\pi M_{eff}$, and the asymmetry of the $g$-factor in bottom-CoFeB(0.93~nm)/MgO(0.90--1.25~nm)/CoFeB(1.31~nm)-top as-deposited systems. Magnetization of CoFeB layers exhibits a specific noncollinear configuration with orthogonal easy axes and with $4\pi M_{eff}$ values of $+2.2$ kG and $-2.3$ kG for the bottom and top layers, respectively. We show that $4\pi M_{eff}$ depends on the asymmetry $g_{\perp }-g_{\parallel }$ of the $g$-factor measured in the perpendicular and the in-plane directions revealing a highly nonlinear relationship. In contrast, the Gilbert damping is practically the same for both layers. Annealing of the films results in collinear easy axes perpendicular to the plane for both layers. However, the linewidth is strongly increased due to enhanced inhomogeneous broadening.

References in corpus (9)

• Enhanced Gilbert Damping in Thin Ferromagnetic Films
• First-principles investigation of the very large Perpendicular Magnetic Anisotropy at Fe|MgO Interfaces
• Precise determination of the spectroscopic g-factor using broadband ferromagnetic resonance spectroscopy
• Ferromagnetic resonance linewidth in ultrathin films with perpendicular magnetic anisotropy
• Experimental Demonstration of the Co-existence of the Spin Hall and Rashba Effects in beta-Tantalum/Ferromagnet Bilayers
• Spin-orbit torque in MgO/CoFeB/Ta/CoFeB/MgO symmetric structure with interlayer antiferromagnetic coupling
• Measurement of orbital asymmetry and strain in Co90Fe10/Ni multilayers and alloys: Origins of perpendicular anisotropy
• Thickness-Dependent Magnetoelasticity and its Effects on Perpendicular Magnetic Anisotropy in Ta|CoFeB|MgO Thin Films
• Ferromagnetic resonance spin pumping in CoFeB with highly resistive non-magnetic electrodes

Cited by in corpus (2)

• Experimental Evidence of Non-Negligible Imaginary Part of Spin Mixing Conductance and Its Impact on Magnetization Dynamics in Heavy-Metal|Ferromagnet Bilayers
• Observation and formation mechanism of 360° domain wall rings in Synthetic Anti-Ferromagnets with interlayer chiral interactions