Arun Jacob Mathew | Searcharxiv

arXiv2026

Observation of large perpendicular magnetic anisotropy and excessive polar magneto-optical effect in Pt/CoFeB/Ru tri-layer system

Heterostructures comprising ferromagnet (FM) and heavy metals (HM) with perpendicular magnetic anisotropy (PMA) and interfacial Dzyaloshinskii-Moriya interaction (iDMI) can host chiral domain walls and topological spin textures, making them highly promising for various spintronics applications. In this paper, we have investigated the magneto-optical properties, the anomalous Hall effect (AHE), and PMA of Pt/CoFeB/Ru multilayers engineered to possess significant iDMI. We utilized the Anomalous Hall effect (AHE), and the polar magneto-optical Kerr effect (p-MOKE), Hall response and the domain wall motion in Pt/CoFeB/Ru-systems. Both MOKE and AHE measurements confirm that the films maintain strong perpendicular magnetization for CoFeB thicknesses below 1.2 nm. The effective magnetic anisotropy K_{\mathrm{eff}} of 0.88 \times 10^6 erg/cm^3 has been achieved without any post-annealing, highlighting the high-quality interface in this multilayer design. The angular dependence of the switching field deviates from the conventional Kondorsky model and is well described using a modified Kondorsky formalism, capturing the role of field-induced domain-wall softening and pinning effects in the reversal process. Furthermore, p-MOKE microscopy imaging during the magnetization reversal process provides detailed insight into domain nucleation and subsequent domain-wall propagation. The observations reveal well-defined, stable magnetic domains that evolve coherently under the applied magnetic field. Such a behavior is expected in the system where interfacial DMI, PMA interact to stabilize the chiral N\'eel-type domain walls, which are essential for fast, low-power domain-wall motion driven by spin-orbit torques.

cond-mat.mtrl-sci↗

arXiv2025

Efficient spin-orbit torque driven magnetization switching of GdFe using phosphorus-implanted platinum layers

The capability of the spin-orbit torque (SOT) generated via phenomena such as the spin Hall effect in heavy metals, in switching the magnetization of an adjacent magnetic material, has been studied extensively over the last decade. The efficiency of SOT generation is commonly quantified in terms of the spin Hall angle {\theta}_SH. In this work, we demonstrate experimentally that implanting platinum (Pt) with phosphorus (P), resulting in Pt (P) d, where d denotes the implantation dose, increases {\theta}_SH by a factor of 7, from 0.06 (d = 0) to 0.43 (d = 10*10^16 ions/cm^2). The enhanced {\theta}_SH, along with factors such as perpendicular magnetic anisotropy and resistivity, lead to reduction of the critical current density for switching the perpendicular magnetization of ferrimagnetic rare earth-transition metal alloy Gd26Fe74, by a factor of nearly 27, from 4.0*1011 A/m^2 (d = 0) to 1.5*10^10 A/m^2 (d = 10*10^16 ions/cm^2). Further, the switching current density at zero thermal fluctuations and thermal stability factor were evaluated and found to be 2.0*10^10 A/m^2 and 61.4 (d = 10*10^16 ions/cm^2), with the latter being sufficiently above the required threshold for commercial memory applications. Our results suggest that Pt (P) could be a strong candidate in realizing efficient SOT driven magnetization switching leading to the development of improved memory and logic devices in the future.

cond-mat.mtrl-sci↗