Tuning Damping and Magnetic Anisotropy in Ultrathin Boron‐Engineered MgO/Co–Fe–B/MgO Heterostructures

Abstract

Nanometer‐thick Co–Fe–B/MgO based structures have been widely accepted as the preferred system for immediate and long‐term goals in magnetic random access memory (MRAM) devices because of excellent spin‐torque efficiency and promise for high‐density MRAM. To realize next‐generation ultra‐low‐power MRAM, further lowering of power consumption in these structures is a crucial ongoing effort. Gilbert damping is one critical material parameter toward lowering energy consumption but is traditionally large (≈10−2) in these Co–Fe–B/MgO systems. Here, Gilbert damping of (1.3 ± 0.3) × 10−3 from a perpendicular double Co–Fe–B/MgO interface system engineered at different boron compositions is reported. Remarkably, this value is achieved with ≈1 nm of Co–Fe–B thickness while maintaining magnetic anisotropy of 0.4 Merg cc−1. An unusual damping trend that scales with layer thickness in high‐boron content films established from both experiments and first‐principles calculations is reported.

Investigation of spin wave dynamics in Au/CoFeB/Au multilayers with perpendicular magnetic anisotropy

“…a slight increase of α with t CoFeB . The reason for this is not yet clear, but it could be a non-local attenuation, as suggested in the recent study 42 . Nevertheless, this effect requires further investigations, which are beyond the scope of this paper.…”

“…a slight increase of α with t CoFeB . The reason for this is not yet clear, but it could be a non-local attenuation, as suggested in the recent study 42 .…”

“…In the context of multilayers based on noble metals, the damping parameter extracted from measurements can stem from various sources, including intrinsic damping associated with the loss of SW energy to the bulk lattice, spin pumping to gold (Au), as well as contributions from two-magnon scattering or non-local damping 41 , 42 . In our study, we utilized double layers of Au with different thicknesses on the lower and upper sides of CoFeB.…”

“…Also, for the exploitation of magnon–phonon, magnon–photon or magnon–magnon couplings, recently explored for quantum magnonics, the narrow linewidth is a crucial parameter to rich strong-coupling regime 28 , 29 . From the spintronic point of view, the materials with low damping are promising for high-speed devices as damping relates to the time of the magnetization switching, so its minimizing can help to optimize spintronic devices based on STT or MTJ 61 , 62 , and also to make these spintronic devices more energetically effective 42 .…”

High temperature stability in few atomic layer MoS2 based thin film heterostructures: structural, static and dynamic magnetization properties

“…Thus, the bilayer combination of CoFeB and MoS 2 could be highly commendable. The preference for employing CoFeB as the FM layer is due to its exotic physical properties, such as its giant TMR ratio (604%), 31 high thermal stability, 32 low Gilbert damping constant (α) ∼ 0.001, 33 high Curie temperature (T C ) ∼ 900 K, 34,35 moderate saturation magnetization (M s ) ∼ 1200 kA m −1 , [35][36][37] low coercivity (H C ), 38 and high spin polarization (η) ∼ 65%. 39 Importantly, among the several FMs, CoFeB is intensively accepted as a FM electrode in MTJ structures.…”