Lakshmanan Saravanan

The multilayers of Ta/Pd/[CoFeB (0.3 nm)/Pd]×5/Pd films were fabricated by ultra-high-vacuum (UHV) magnetron sputtering and subsequently annealed at temperatures (T_A) ranging from 100 °C to 400 °C. The magnetic measurements were performed with the applied field oriented parallel and perpendicular to the film plane to evaluate the out-of-plane magnetic anisotropy (PMA). A maximum effective PMA energy density (K_eff) of ≈7.82 × 10⁵ erg/cc and a small out-of-plane saturation magnetisation (M_s⊥) were achieved at the optimal T_A. The evolution of PMA is associated with interfacial atomic migration and oxidation processes, as confirmed by X-ray photoelectron spectroscopy (XPS). Annealing at 300 °C initiates the formation of TaB and TaOB interfacial phases, whereas annealing at 400 °C promotes the enhanced growth of Ta₂O₅ and TaB, along with additional TaOB formation owing to increased oxygen migration. These thermally stable Ta–boride phases lead to pronounced modifications in the magnetic properties. Consequently, oxygen migration and interfacial reactions at elevated temperatures primarily alter the chemical states of the B 1s, Pd 3d, and Ta 4f orbitals, thereby influencing the PMA. The field-dependent electrical resistance (MR) study demonstrates that annealing at 100–400 °C optimises the anisotropic effect in the [CoFeB/Pd]×5-based multilayers. However, higher temperatures can trigger atomic intermixing, which degrades PMA strength and the resistance response. Moreover, the samples were further characterised by their structural, anomalous Hall effect (AHE) and magnetoresonance (MRO) properties. Overall, controlled T_A-driven oxygen diffusion and interfacial oxidation enable effective tuning of the PMA, MR, and MRO properties of ultrathin [CoFeB/Pd]×5 multilayers, highlighting their strong potential for spin–orbit torque (SOT), Dzyaloshinskii–Moriya interaction (DMI), and magnetic skyrmion-based spintronic devices.

The thin films of amorphous ferromagnet Co 60 Fe 20 B 20 have been accepted as a promising material for switching applications in spintronics. The choice of different growth parameters employed in the growth of Co 60 Fe 20 B 20 films can, however, significantly influence the structural, topographical, electron-transport, magneto-optic, and magnetization dynamic properties of the Co 60 Fe 20 B 20 thin films. In this study, we have thoroughly investigated the influence of Argon gas working pressure ( ) employed during sputtering of Co 60 Fe 20 B 20 thin films grown on Si substrate at room temperature. The longitudinal magneto-optic Kerr effect measurements indicate that all films exhibit uniaxial anisotropy caused by the self-steering effect arising due to the oblique angle deposition. The coercive field, which is found to be sensitive to during growth, reached a minimum value of 1.2 mT at 1.1 mTorr. The ferromagnetic resonance measurements revealed that has a direct impact on the inhomogeneous linewidth, anisotropy, and the Gilbert damping constant . The lowest value of ~ is observed in films sputtered at = 1.1 mTorr with negligible inhomogeneity and low anisotropy . The observed value of damping is better than the reported values in Co x Fe y B z , which stems from the unique composition of our Co 60 Fe 20 B 20 and Ar gas treatment. At this optimum value of , the surface roughness of the films exhibits the smallest value of 4.1 . The observed changes in the static and dynamic magnetization properties in these Co 60 Fe 20 B 20 films on varying the are correlated to the growth-rate-dependent changes in internal stress in the film. The present results highlight the crucial correlation of the with the film’s surface roughness, coercivity, and magnetization dynamics parameters. The choice of the value of Argon-pressure employed during sputtering of Co 60 Fe 20 B 20 films at room temperature is thus demonstrated as the simplest control parameter for tuning the quality and magnetic properties of CFB thin films which will eventually lead to development of spintronic devices with the desired dynamic properties for switching applications.

Perpendicular magnetic anisotropy (PMA) in Co₂FeAl (CFA)/MgO stacks deposited on the MgO buffer layer is studied as a function of MgO over‐layer thickness and annealing temperature. It reveals that MgO over‐layer (thickness between 0 and 1.5 nm) improves the PMA of CFA grown on MgO buffer layer. It is identified that MgO over‐layer thickness is a crucial factor that affects the magnetic anisotropy. The maximum effective PMA energy density (K_eff) of ≈1.22 × 10⁶ erg cm⁻³ is observed at 400 °C. Besides, PMA is also realized for room temperature (RT) films. Moreover, enhancement in the perpendicular saturation magnetization (M_s┴) with PMA is effectively induced by the CFA/MgO or CFA/Mo interface and is discussed in detail. The grain distribution and surface roughness are investigated by atomic force microscopy (AFM) for without and with MgO over‐layer in MgO/CFA/t_MgO (0 and 0.5 nm)/Mo stacks at higher annealing temperature. Therefore, this MgO/CFA/MgO can be an ideal system for the p‐MTJs‐based new generation low power consuming large density data storage spintronic devices with improved thermal stability.