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Graphene nanoribbons (GNRs), when synthesized with atomic precision by bottom–up chemical approaches, possess tunable electronic structure, and high theoretical mobility, conductivity, and heat dissipation capabilities, which makes them an excellent candidate for channel material in post-silicon transistors. Despite their immense potential, achieving highly transparent contacts for efficient charge transport—which requires proper contact selection and a deep understanding of the complex one-dimensional GNR channel-three-dimensional metal contact interface—remains a challenge. In this study, we investigated the impact of different electron-beam deposited contact metals—the commonly used palladium (Pd) and softer metal indium (In)—on the structural properties and field-effect transistor performance of semiconducting nine-atom wide armchair GNRs. The performance and integrity of the GNR channel material were studied by means of a comprehensive Raman spectroscopy analysis, scanning tunneling microscopy (STM) imaging, optical absorption calculations, and transport measurements. We found that, compared to Pd, In contacts facilitate favorable Ohmic-like transport because of the reduction of interface defects, while the edge structure quality of GNR channel plays a more dominant role in determining the overall device performance. Our study provides a blueprint for improving device performance through contact engineering and material quality enhancements in emerging GNR-based technology. [ABSTRACT FROM AUTHOR]

We offer a perspective on the prospects of ultrafast spintronics and opto-magnetism as a pathway to high-performance, energy-efficient, and non-volatile embedded memory in digital integrated circuit applications. Conventional spintronic devices, such as spin-transfer-torque magnetic-resistive random-access memory (STT-MRAM) and spin–orbit torque MRAM, are promising due to their non-volatility, energy-efficiency, and high endurance. STT-MRAMs are now entering into the commercial market; however, they are limited in write speed to the nanosecond timescale. Improvement in the write speed of spintronic devices can significantly increase their usefulness as viable alternatives to the existing CMOS-based devices. In this article, we discuss recent studies that advance the field of ultrafast spintronics and opto-magnetism. An optimized ferromagnet–ferrimagnet exchange-coupled magnetic stack, which can serve as the free layer of a magnetic tunnel junction (MTJ), can be optically switched in as fast as ∼3 ps. Integration of ultrafast magnetic switching of a similar stack into an MTJ device has enabled electrical readout of the switched state using a relatively larger tunneling magnetoresistance ratio. Purely electronic ultrafast spin–orbit torque induced switching of a ferromagnet has been demonstrated using ∼6 ps long charge current pulses. We conclude our Perspective by discussing some of the challenges that remain to be addressed to accelerate ultrafast spintronics technologies toward practical implementation in high-performance digital information processing systems. [ABSTRACT FROM AUTHOR]

An experiment was conducted to find out the effects of various postharvest treatments on the biochemical and bioactive compounds of custard apple cv. Balanagar fruits. In the present experiment, three chemicals viz. oxalic acid (OA) (2.5 mM, 5.0 mM, 7.5 mM, and 10 mM; salicylic acid (SA) (0.5 mM, 1.0 mM, 1.5 mM, and 2.0 mM) and Sodium Nitro Prusside (SNP) at 0.5 mM, 1.0 mM, 1.5 mM, and 2.0 mM along with control were applied. Fruits were stored at ambient condition (Temp. 25 ± 2°C and relative humidity (RH) 44 ± 2%). Results indicated that fruits treated with SNP (2.0 mM) had significantly (p≤ 0.05) higher total soluble solids (30.80°B), titratable acidity (TA) (0.33%) and retained higher total sugar content (TS) (25.09%) at the end of the 9th day of storage. At the end of storage, the least reduction in total phenol content (TPC) (492.52 mg gallic acid equivalent (GAE)/100 g (11.62%) was found in SNP (2.0 mM) treated fruits. Likewise, SNP (2.0 mM) significantly (p≤ 0.05) retained higher ascorbic acid (AA) (43.20 mg/100 g), antioxidant activity (AOX) (0.92 µmol Trolox Equivalent (TE)/g), total flavonoids (TF) (71.49 µg CE/100 g) and tannin content (TC) (1.28 mg/g) compared to control during 9 days of storage. Thus, in the present investigation, SNP treatment was most suited to preserve the nutritional quality and bioactive compounds. [ABSTRACT FROM AUTHOR]

We investigate localized in-plane strains on the microscale, induced by arrays of biased surface electrodes patterned on piezoelectrics. Particular focus is given to the influence that adjacent electrode pairs have on one another to study the impact of densely packed electrode arrays. We present a series of X-ray microdiffraction studies to reveal the spatially resolved micrometer-scale strain distribution. The strain maps with micrometer-scale resolution highlight how the local strain profile in square regions up to 250 × 250 μ m 2 in size is affected by the surface electrodes that are patterned on ferroelectric single-crystal [Pb(Mg1/3Nb2/3)O3]x-[PbTiO3]1−x. The experimental measurements and simulation results show the influence of electrode pair distance, positioning of the electrode pair, including the angle of placement, and neighboring electrode pair arrangements on the strength and direction of the regional strain. Our findings are relevant to the development of microarchitected strain-mediated multiferroic devices. The electrode arrays could provide array-addressable localized strain control for applications including straintronic memory, probabilistic computing platforms, microwave devices, and magnetic-activated cell sorting platforms. [ABSTRACT FROM AUTHOR]

Spherical assemblies named "reverse micellar vesicles" from self-assembling psuedopeptidic bottlebrush polymers are reported. These assemblies exhibited the combined features of both micelles and vesicles viz. molecular arrangement of classical micelles and dimensions similar to that of classical vesicles. Comprehensive ultramicroscopic and spectroscopic analyses were performed to delineate the hierarchical mechanism of their formation. [ABSTRACT FROM AUTHOR]

Spin current has emerged as a leading candidate for manipulation of spins in a nano-magnet. We here experimentally show another utility of spin current, viz., it can be used for the generation of phonons. Within the same experimental setup, we also demonstrate the inverse effect of generation of spin current by phonons. To demonstrate these effects, we measured the scattering-matrix of a two-port device with interdigital transducers as one port and an array of Ni/Pt lines as a second port made on a piezoelectric substrate. The off-diagonal elements which correspond to transmission between the ports were found to have 180° relative phase shift. The transmission of electrical signals from port 2 to 1 corresponds to the generation of phonons from spin-current, while transmission from port 1 to 2 corresponds to the inverse effect. These results could be useful for designing spin-current based gyrators. We further show the reciprocity between spin transfer torque and spin pumping effects. [ABSTRACT FROM AUTHOR]

In this work we have studied the effect of external applied magnetic field on the locking range of spintronic feedback nano oscillator. Injection locking of spintronic feedback nano oscillator at integer and fractional multiple of its auto oscillation frequency was demonstrated recently. Here we show that the locking range increases with increasing external magnetic field. We also show synchronization of spintronic feedback nano oscillator at integer (n=1,2,3) multiples of auto oscillation frequency and side band peaks at higher external magnetic field values. We have verified experimental results with macro-spin simulation using similar conditions as used for the experimental study. [ABSTRACT FROM AUTHOR]

The magnetization of a nano-magnet can be manipulated and even switched by spin-orbit torques. Hence, accurate characterization of these torques is essential from the application perspective. In this work, we present an alternative method to characterize the spin-orbit torque utilizing the planar Hall effect of a ferromagnet. We show that while the ferromagnet is excited to resonance due to spin-orbit torque, its planar Hall resistance also varies, which leads to sensitive detection of spin-orbit torque. We further demonstrate that planar Hall geometry enables us to estimate spin Hall angle measuring change in magnetic damping very accurately while rf current and dc current are applied perpendicular to each other. Using these techniques, we show that in the Pt/Py bilayer, the spin-Hall effect dominates over interfacial field like spin-orbit torques, which is consistent with previous studies. [ABSTRACT FROM AUTHOR]

The article focuses on demonstrating ultrafast spin-orbit torque (SOT)-induced coherent magnetization switching in a ferromagnet, which has significant implications for electrically controllable nonvolatile magnetic memories. Topics discussed include the use of an ultrafast electrical pulse to induce SOT, the role of thermal anisotropy torque in magnetization switching, and the potential for enhancing the writing speed of SOT magnetic random-access memory devices.

The structured beams of light endowed with vector field singularities can be expressed as a superposition of spin and orbital angular momentum states. This article investigates the effect of perturbation of vector field singularities by superposing it with a homogeneously polarized beam and discusses its possible applications in studying the chiroptical effects. This perturbation leads to the splitting of vector field singularities (V-points) into stable lower-index ellipse field singularities (C-points). The strength of perturbation decides the separation between the two C-points in the resultant beam. It is found that the unfolding of V-points into lower-index C-points is always accompanied by a measurable centroid shift in the total and component intensity distribution of the resultant beam. Moreover, the centroid shift is more pronounced in the component intensity, whose state of polarization matches the state of polarization of the perturbing beam. The strength of perturbation can be measured by analyzing the radial shift in the centroid of the beam. It is observed that in the process of perturbation, the polarization singularity index is always conserved while the net helicity in the resultant beam is decided by the helicity of the perturbing beam. The strength of the perturbing beam can be modified by introducing a chiral sample in the beam path which may be useful to investigate the chiroptical effects. • Perturbation of V-points with homogeneously polarized beam is demonstrated. • Splitting of vector field singularities into ellipse field singularities is observed • This splitting is accompanied by a measurable centroid shift of the perturbed beam. • This result can be used to assess the strength of the perturbing beam. • The index and helicity conservation rules are discussed. [ABSTRACT FROM AUTHOR]

Bottom-up assembled nanomaterials and nanostructures allow for the studies of rich and unprecedented quantum-related and mesoscopic transport phenomena. However, it can be difficult to quantify the correlations between the geometrical or structural parameters obtained from advanced microscopy and measured electrical characteristics when they are made into macroscopic devices. Here, we propose a strategy to connect the nanomaterial morphologies and the device performance through a Monte Carlo device model and apply it to understand the scaling trends of bottom-up synthesized armchair graphene nanoribbon (GNR) transistors. A new nanofabrication process is developed for GNR transistors with channel length down to 7 nm. The impacts of the GNR spatial distributions and the device geometries on the device performance are investigated systematically through comparison of experimental data with the model. Through this study, challenges and opportunities of transistor technologies based on bottom-up synthesized GNRs are pinpointed, paving the way to the further improvement of the GNR device performance for future transistor technology nodes. [Display omitted] [ABSTRACT FROM AUTHOR]