Disentanglement of intrinsic and extrinsic side-jump scattering induced spin Hall effect in N-implanted Pt

The rapidly evolving utilization of spin Hall effect (SHE) arising from spin-orbit coupling in 5d transition metals and alloys have made giant strides in the development of designing low-power, robust and non-volatile magnetic memory. Recent studies, on incorporating non-metallic lighter elements such as oxygen, nitrogen and sulfur into 5d transition metals, have shown an enhancement in damping-like torque efficiency {\theta}_DL due to the modified SHE, but the mechanism behind this enhancement is not clear. In this paper, we study {\theta}_DL at different temperatures (100-293 K) to disentangle the intrinsic and extrinsic side-jump scattering induced spin Hall effect in N-implanted Pt. We observe a crossover of intrinsic to extrinsic side-jump mechanism as the implantation dose increases from 2*10^16 ions/cm2 to 1*10^17 ions/cm2. A sudden decrease in the intrinsic spin Hall conductivity is counterbalanced by the increase in the side-jump induced SHE efficiency. These results conclude that studying {\theta}_DL as a function of implantation dose, and also as a function of temperature, is important to understand the physical mechanism contributing to SHE, which has so far been unexplored in incorporating non-metallic element in 5d transition metals

Highly dose dependent damping-like spin-orbit torque efficiency in O-implanted Pt

Damping-like torque (DLT) arising from the spin Hall effect (SHE) in heavy metals and their alloys has been widely explored for applications in spin–orbit torque MRAM, auto-oscillations, spin waves, and domain wall motion. In conventional materials, the DLT efficiency is limited by intrinsic properties, while attaining strong spin–orbit coupling and higher spin-charge interconversion, with no compromise to electric properties, is the need of the hour. In this Letter, we report more than 3.5 times increase in DLT efficiency, θDL, of modified Pt-oxide by employing a better approach of low energy 20 keV O+ ion implantation. The highest fluence of O+ implantation (1 × 1017 ions cm−2) in Pt enhanced the DLT efficiency from 0.064 to 0.230 and improved the spin transmission for a smaller trade-off in the longitudinal resistivity (ρPt to ρPt−Oxide) from 55.4 to 159.5 μΩ cm, respectively. The transverse spin Hall resistivity, ρSH, is found to be proportional to the square of the longitudinal resistivity, i.e., ρimpSH∝ρ2imp, implying that the enhanced SHE in O-implanted Pt is due to a side-jumping mechanism. Further, no break in the twofold as well as mirror symmetry of torques from the O-implanted Pt allows the use of spin-torque ferromagnetic resonance-based line shape analysis to quantify such torques

Enhanced Spin Hall Effect in S-Implanted Pt

High efficiency of charge–spin interconversion in spin Hall materials is a prime necessity to apprehend intriguing functionalities of spin–orbit torque for magnetization switching, auto-oscillations, and domain wall motion in energy-efficient and high-speed spintronic devices. To this end, innovations in fabricating advanced materials that possess not only large charge–spin conversion efficiency but also viable electrical and spin Hall conductivity are of importance. Here, a new spin Hall material designed by implanting low energy 12 keV sulfur ions in heavy metal Pt, named as Pt(S), is reported that demonstrates eight times higher conversion efficiency as compared to pristine Pt. The figure of merit, spin Hall angle (θSH), up to θPt(S)SH of 0.502 together with considerable electrical conductivity σPt(S)xx of 1.65 × 10 6 Ω–1 m–1 is achieved. The spin Hall conductivity σPt(S)SH increases with increasing σPt(S)xx, as σPt(S)SH∝σPt(S)1.7xx, implying an intrinsic mechanism in a dirty metal conduction regime. A comparatively large σPt(S)SH of 8.32 × 10 5 (ℏ/2e) Ω–1 m–1 among the reported heavy-metals-based alloys can be useful for developing next-generation spintronic devices using spin–orbit torque

Nanocomposite ZnO–SnO2 Nanofibers Synthesized by Electrospinning Method

We report the characterization of mixed oxides nanocomposite nanofibers of (1 − x) ZnO-(x)SnO2 (x ≤ 0.45) synthesized by electrospinning technique. The diameter of calcined nanofibers depends on Sn content. Other phases like SnO, ZnSnO3, and Zn2SnO4 were absent. Photoluminescence studies show that there is a change in the blue/violet luminescence confirming the presence of Sn in Zn-rich composition. Present study shows that the crystalline nanocomposite nanofibers with stoichiometry of (1 − x)ZnO-(x)SnO2 (x ≤ 0.45) stabilize after the calcination and possess some morphological and optical properties that strongly depend on Sn content

Understanding electronic structure of Bi(Pb)-Sr-Ca-Cu-O compounds by XANES

[[abstract]]We report X-ray absorption near edge structure (XANES) of Cu and O K-edges of superconducting [Bi(Pb)]2Sr2CaCu2O8+δ (Bi-2212) and [Bi(Pb)]2Sr2Ca2Cu3O10+δ (Bi-2223) compounds. The spectral features of these two systems are compared based on existing assignments available in the literature. Spectroscopically, the intensity of Cu 1s→3dx2−y2 from Cu K-edge spectra is different in these cuprates and the pre-edge peaks of O K-edges are better resolved in Bi-2223 attributed to arise from Cu–O, and metallic Bi–O layers.[[notice]]補正完畢[[journaltype]]國外[[incitationindex]]SCI[[booktype]]紙本[[countrycodes]]NL

Thickness-Dependent Electronic Structure of Intermetallic CeCo2 Nanothin Films Studied by X-ray Absorption Spectroscopy

[[abstract]]We report the electronic structure study of intermetallic CeCo2 nanothin films of various thicknesses by X-ray absorption near-edge structure (XANES) spectroscopy at Ce L3-, Co K-, and L2,3-edges. The Ce L3-edge absorption spectra reveal that the contribution of tetravalent Ce component increases with the film thickness, and all investigated nanothin films exhibit intermediate valence nature. Variation of the spectral intensities observed at the Co K-edge threshold implies modification in the Co 3d states and the enhancement of 3d-4f-5d hybridization. The Co 3d and Ce 4f occupation numbers were estimated from these spectroscopic results. The present study brings out how the surface-to-bulk ratio and the charge transfer between Ce and Co ions affect the electronic structure of nanothin films.[[journaltype]]國外[[incitationindex]]SCI[[incitationindex]]EI[[ispeerreviewed]]Y[[booktype]]紙本[[countrycodes]]US

Enhancement of Electrical Parameters of Ni/n-GaN SBDs under Remote and not In-flux Gamma Irradiation

Remote and not in-flux gamma irradiation effects have been examined on the cumulative dose ranges from 250 Gy to 1 kGy by current-voltage (I-V) and capacitance-voltage (C-V) characteristics for Ni/n-GaN Schottky barrier diodes (SBDs). The interface and charge transport properties of Ni/n-GaN SBDs are significantly changed after gamma irradiation. In addition, the reverse current conduction mechanism indicates that the emission of Poole-Frenkel is dominant in lower voltages and Schottky emission for different doses at the higher voltage. The electrical parameters, such as barrier height and series resistance, decreases significantly at 500 Gy. Due to the internal irradiation of Compton electrons caused by primary gamma photons, low-dose gamma irradiation reveals the enhancement of device characteristics. Nonetheless, for higher doses of gamma irradiation above 500 Gy, degradation of Ni/n-GaN characteristics was observed

Laser Transmission Welding of Semi-Crystalline Polymers and Their Composites: A Critical Review

The present review provides an overview of the current status and future perspectives of one of the smart manufacturing techniques of Industry 4.0, laser transmission welding (LTW) of semi-crystalline (SC) polymers and their composites. It is one of the most versatile techniques used to join polymeric components with varying thickness and configuration using a laser source. This article focuses on various parameters and phenomena such as inter-diffusion and microstructural changes that occur due to the laser interaction with SC polymers (specifically polypropylene). The effect of carbon black (size, shape, structure, thermal conductivity, dispersion, distribution, etc.) in the laser absorptive part and nucleating agent in the laser transmissive part and its processing conditions impacting the weld strength is discussed in detail. Among the laser parameters, laser power, scanning speed and clamping pressure are considered to be the most critical. This review also highlights innovative ideas such as incorporating metal as an absorber in the laser absorptive part, hybrid carbon black, dual clamping device, and an increasing number of scans and patterns. Finally, there is presented an overview of the essential characterisation techniques that help to determine the weld quality. This review demonstrates that LTW has excellent potential in polymer joining applications and the challenges including the cost-effectiveness, innovative ideas to provide state-of-the-art design and fabrication of complex products in a wide range of applications. This work will be of keen interest to other researchers and practitioners who are involved in the welding of polymers