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We present our findings on how orange peel coupling (OPC) between the ferromagnetic layers affects spin transfer torque-assisted magnetization reversal dynamics in CoPt, CoFeB, and EuO pentalayer nanopillar devices. We accomplish this by solving the Landau-Lifshitz-Gilbert-Slonczewski (LLGS) equation (dynamical equation) using the Runge-Kutta fourth-order numerical technique. To begin, we examine the influence of OPC on switching times by simulating the LLGS equation separately for each pentalayer device, both with and without OPC. The magnetization switching times for CoPt, CoFeB, and EuO devices in the absence of OPC are 58 ps, 82 ps, and 154 ps, respectively. When introducing OPC in the pentalayer alloys, we observe a reduction in switching times of 3.5%, 11%, and 40% for CoPt, CoFeB, and EuO devices, respectively. Furthermore, we calculate the current density required to reverse the magnetization of the free layer in CoPt, CoFeB, and EuO pentalayer devices, which is found to be 0.78 × 10 12 A / m 2 , 1.8 × 10 12 A / m 2 , and 4.4 × 10 12 A / m 2 , respectively. In addition, we investigate how the thicknesses of the free and spacer layers, as well as the wavelength and amplitude of interface roughness, affect the magnetization switching time. Understanding the effects of OPC paves the way for the practical implementation of spin transfer torque (STT)-based memory devices. [ABSTRACT FROM AUTHOR]

The oscillatory interlayer exchange coupling (OXC) between ferromagnetic layers sandwiched by non-magnetic spacer layers plays a significant role in spintronic device function. In this work, the effect of OXC on the current-induced magnetization switching process in four different pentalayer nanopillar alloys is numerically investigated by solving the dynamical equation governed by the Landau–Lifshitz–Gilbert–Slonczewski (LLGS) equation. The four nanopillars consist of four ferromagnetic alloys, CoPt, CoFeB, Fe 85 B 13 Ni 2 and EuO, which serve as pinned layers and free layers, with copper forming a spacer layer between all the layers. The critical current density required to switch the magnetization of the free layer is computed for all the devices and the values are 0.6 × 10 11 Am - 2 , 1.31 × 10 11 Am - 2 , 2.24 × 10 11 Am - 2 , 3.27 × 10 11 Am - 2 for CoPt, CoFeB, Fe 85 B 13 Ni 2 and EuO device, respectively. Then we studied how the thickness of the Cu layer influences the OXC field. Furthermore, we investigated the effect of Cu layer thickness on critical current density and magnetization switching time for all the four devices by numerically solving the LLGS equation and they exhibit oscillating behaviour. We can reduce the critical current density and switching time substantially by controlling the OXC field acting on the free layer and choosing the magnetic material having low saturation magnetization as the free layer. The OXC field is optimised by fixing the Cu spacer thickness from 1.7 to 1.9 nm in the pentalayer nanopillar device. [ABSTRACT FROM AUTHOR]

We investigated the influence of oscillatory interlayer exchange coupling (OXC) on spin transfer torque (STT)-assisted magnetization switching in the pentalayer nanopillar structure. The impact of OXC between the ferromagnetic layers in the pentalayer nanopillar is realised by solving the associated governing equation, namely Landau-Lifshitz-Gilbert-Slonczewski (LLGS) equation. First, we calculated the critical current density needed to switch the magnetization of the free layer in the absence of OXC by analytically solving the LLGS equation and its value is J c = 0.46 × 10 11 A m - 2 . Then, we studied the influence of thickness of the spacer layer on the OXC field term and how it affects the critical current density and magnetization switching behaviour by numerical simulations of LLGS equation. By controlling OXC, we reduce critical current density and magnetization switching time from peak values to 86% and 82%, respectively, which is accomplished by constructing a multilayer with optimal spacer layer thickness of 1.7 to 1.9 nm. This work paves a potential way for practical implementation of STT-based MRAMs, nano-oscillators, and logic devices. [ABSTRACT FROM AUTHOR]

The magnetization switching dynamics of the free layer in the pentalayer nanopillar is studied by numerically solving the dynamical equation governed by the Landau–Lifshitz–Gilbert–Slonczewski equation. The magnetization switching time in the absence of orange peel coupling for an applied current density of 7 × 10 11 A m - 2 is 207 ps. The presence of orange peel coupling reduces the switching time to 116 ps for the same applied current density. The main reason for the reduction of the switching time in the presence of orange peel coupling is generation of additional coupling field perpendicular to the easy axis due to the correlated interface roughness. The impact of spacer and free layer thickness on switching time is also studied. We found that switching time reduces, when the thickness of the spacer and free layer is decreased. [ABSTRACT FROM AUTHOR]

The effect of biquadratic coupling on spin transfer torque-assisted magnetization switching in the pentalayer nanopillar device is studied by numerically solving the magnetization switching dynamics of the free layer governed by the Landau- Lifshitz-Gilbert-Slonczewski (LLGS) equation. Magnetization switching time in the absence of biquadratic coupling for an applied current density of 10 × 1011Am− 2 is 186 ps. Biquadratic coupling arises due to the uncorrelated roughness in the ferromagnetic layers and it reduces the switching time to 160 ps. Further, the impact of the period of roughness and spacer layer thickness on switching time are studied. [ABSTRACT FROM AUTHOR]

The impact of current on static and kinetic depinning fields of a domain wall in a one- dimensional ferromagnetic nanostrip is investigated analytically and numerically by solving the Landau-Lifshitz-Gilbert equation with adiabatic and non-adiabatic spin-transfer torques. The results show that in the absence of current, the static depinning field is greater than the kinetic depinning field. Both the depinning fields decrease by increasing the current applied in a direction opposite to the direction of the applied field. Both the depinning fields can also be tuned by the current to make them equal. [ABSTRACT FROM AUTHOR]

We have theoretically devised the Magneto Resistance (MR)-based Tilted Polarizer Spin Torque Nano-Oscillator (TP STNO) with homogeneous and heterogeneous spin valve structure by varying the Tilted Pinned Layer (TPL) (β ) and (θ ), an angle between the free layer magnetization, and the free layer easy axis of the device. Here, we have included the resistance of the device via current and studied how it affects the frequency and its tunability with power. In this article, we have numerically investigated the magnetization precession dynamics led by the Spin Transfer Torque (STT) phenomena by solving the famous Landau–Lifshitz–Gilbert–Slonczewski (LLGS) equation. By varying TPL angle (β ) in MR-TP STNO from 0 ∘ to 90 ∘ , the free layer precessional dynamics of the device is studied. For all the tilt angles, the frequency range is accessible as well as highly tunable in GHz regime for both the homo- and heterogeneous devices. As far as the homogeneous device is concerned, the maximum frequency of about 24.75 GHz with the corresponding power of about 1.122 ( μ W / mA 2 )/GHz for β = 60 ∘ and θ = 90 ∘ is obtained which is low when compared with the authors previous work [17] because of the inclusion of resistance into the device. For same β and θ , the maximum operating frequency of about 202.3 GHz and its corresponding power of about 2.426 ( μ W / mA 2 )/GHz are obtained for the heterogeneous device where the resistance of the device is low as compared to homogeneous device. From the reported results, it is evident that the device based on heterogeneous emits more frequency and power than the homogeneous device. The obtained results are highly alluring paves a smart way for the implementation of microwave nano-scale sources for the foreseeable spintronic devices. [ABSTRACT FROM AUTHOR]

A key task in the fact-checking workflow is to establish whether the claim under investigation has already been debunked or fact-checked before. This is essentially a retrieval task where a misinformation claim is used as a query to retrieve from a corpus of debunks. Prior debunk retrieval methods have typically been trained on annotated pairs of misinformation claims and debunks. The novelty of this paper is an Unsupervised Method for Training Debunked-Narrative Retrieval Models (UTDRM) in a zero-shot setting, eliminating the need for human-annotated pairs. This approach leverages fact-checking articles for the generation of synthetic claims and employs a neural retrieval model for training. Our experiments show that UTDRM tends to match or exceed the performance of state-of-the-art methods on seven datasets, which demonstrates its effectiveness and broad applicability. The paper also analyses the impact of various factors on UTDRM's performance, such as the quantity of fact-checking articles utilised, the number of synthetically generated claims employed, the proposed entity inoculation method, and the usage of large language models for retrieval. [ABSTRACT FROM AUTHOR]

We investigate the effect of spin torque on the switching dynamics of magnetic solitons in a weak ferromagnetic nanowire under the influence of an electromagnetic wave (EMW). The magnetization dynamics of the current-driven ferromagnetic nanowire and the EMW propagation is governed by the celebrated Landau-Lifshitz-Gilbert (LLG) vector equation and the Maxwell's equations, respectively. We recast the set of LLG and Maxwell equations onto the extended derivative nonlinear Schr o ¨ dinger (EDNLS) equation. We employ the nonlinear perturbation analysis along the lines of Kodama and Ablowitz and analyze the interplay of the Dzyaloshinskii-Moriya interaction (DMI) along with the spin transfer torque on the magnetization reversal dynamics by solving the associated evolution equations for the soliton parameters. We also demonstrate the spin-polarized current triggers an ultrafast switching of EM solitons in the ferromagnetic nanowire in the range of 0.58 - 0.12 n s , and the Gilbert damping supports the EM soliton switching to sustain indefinitely. We invoke the Jacobi elliptic function method to explore the propagation of breather-like solitonic localized modes along the ferromagnetic nanowire. [ABSTRACT FROM AUTHOR]

This work investigates theoretically the possibility of a dual-barrier magnetic tunnel junction (MTJ) to act as a spin-torque oscillator (STO) which could produce microwaves. We have identified the parameters that control the frequency of oscillations and tuned them to get a maximum frequency. To improve the output power and reduce the distortions, phase locking the STO through external alternating current is done. It is found that the synchronisation occurs rapidly leading to a reduced response time, which is a significant result. Interestingly, magnetisation dynamics becomes chaotic for specific choice of parameters and the period doubling bifurcation is studied to explore the route to chaos. [ABSTRACT FROM AUTHOR]

In this work, the Fe-based single atomic chains are designed in the semiconductive CoFeTiAl quaternary Heusler matrix by substituting Ti, Al, or Ti-Al with Fe in [001] crystallographic direction. We have investigated the electronic structures and magnetic characteristics of the Fe-based supercells by using the first-principles calculations. Our results show that all the three kinds of single atomic chains Fe-Al, Fe-Ti, and Fe-Fe atomic chains show a half-metallicity with 100 % spin polarization. A conductive nanopillar is formed and dilutedly distributed in CoFeTiAl matrix. The width of the nanopillar is about half of the lattice parameter, and the length of it will be adjustable. It would be an ideal method to design the new direct-current-magnetic memory device. [ABSTRACT FROM AUTHOR]

In this work we performed a detailed numerical analysis on the static and dynamic properties of magnetic antidot arrays as a function of their geometry. In particular, we explored how by varying the shape of these antidot arrays from circular holes to stadium-shaped holes, we can effectively control the magnetic properties of the array. Using micromagnetic simulations we evidenced that coercivity is very sensitive to the shape of antidots, while the remanence is more robust to these changes. Furthermore, we studied the dynamic susceptibility of these systems, finding that it is possible to control both the position and the number of resonance peaks simply by changing the geometry of the holes. Thus, this work provides useful insights on the behavior of antidot arrays for different geometries, opening routes for the design and improvement of two-dimensional technologies. [ABSTRACT FROM AUTHOR]

We report spin-wave excitations in annular antidot lattice fabricated from 15 nm-thin Ni80Fe20 film. The nanodots of 170 nm diameters are embedded in the 350 nm (diameter) antidot lattice to form the annular antidot lattice, which is arranged in a square lattice with edge-to-edge separation of 120 nm. A strong anisotropy in the spin-wave modes are observed with the change in orientation angle (ϕ) of the in-plane bias magnetic field by using Time-resolved Magneto-optic Kerr microscope. A flattened four-fold rotational symmetry, mode hopping and mode conversion leading to mode quenching for three prominent spin-wave modes are observed in this lattice with the variation of the bias field orientation. Micromagnetic simulations enable us to successfully reproduce the measured evolution of frequencies with the orientation of bias magnetic field, as well as to identify the spatial profiles of the modes. The magnetostatic field analysis, suggest the existence of magnetostatic coupling between the dot and antidot in annular antidot sample. Further local excitations of some selective spin-wave modes using numerical simulations showed the anisotropic spin-wave propagation through the lattice. [ABSTRACT FROM AUTHOR]