Arnab Ganguly

We simulate the functionality of an artificial neuron and synapse using spin-orbit torque-based spintronic devices and implement a fully connected artificial neural network (ANN). These neuro-synaptic devices are emulated via transverse domain wall dynamics within a magnetic nanotrack comprised of heavy-metal (HM)/ferromagnet (FM) heterostructures, parameterized using Pt-based alloys, and CoFeB for the HM layer and FM layer, respectively. The ReLU activation function of the neuron is mimicked using domain wall (DW) motion. The synapse is modeled using current-induced DW dynamics with a corrugated HM/FM nanotrack, where the electrical conductance of the pinned DW across pinning points acts as stable synaptic weights. The fully connected ANN, using conventional float32 weights, achieves an accuracy of ~97% and ~86% for the MNIST and Fashion-MNIST datasets, serving as a test bed for our simulations. To implement a sparse, low-memory-footprint ANN, we quantize the trained weights into discrete levels, achieving an accuracy of ~95% and ~62% for MNIST and Fashion-MNIST, respectively, which is restored back to the baseline accuracy after fine-tuning. We demonstrate the write and read energies of the ANN are on the order of pJ, with an operational latency of 8 ns.

Artificial magnetic lattices fabricated via nanosphere lithography are gaining attention for their tunable magnetic properties, low cost, and reproducibility compared to conventional nanofabrication methods. This study examines magnetization reversal mechanisms in cobalt nanostructures produced through nanosphere lithography, emphasizing the roles of lattice constant and in-plane magnetic field orientation. Using micromagnetic simulations, the study systematically analyzes how nanosphere diameter (defining lattice constant) and field angle influence hysteretic parameters and switching rate. Results show a distinct transition: smaller lattice constants yield gradual, multi-step reversal, whereas larger lattice constants produce sharper, synchronized switching. Angular dependence further reflects lattice symmetry, with larger lattices exhibiting strong hexagonal-symmetry responses, while smaller ones show reduced sensitivity due to enhanced out-of-plane spin component. The findings distinguish single-mode from multi-mode reversal regimes and provide valuable insights for designing advanced magnetic lattices for memory and spintronic applications.

Magnetic nanoparticles and nanochains hold significant importance in data storage and biomedical applications due to their small size, high aspect ratio, and distinctive reversal properties. However, these properties are significantly affected by the surface morphology and fine orientational features of the particles. This study systematically examines the magnetic reversal and hysteretic properties of Ni nanostar-chains and their constituent particles, focusing on the surface characteristics and geometric configurations resulting from chemical synthesis. The investigation reveals the influence of surface roughness, manifested as spikes, on the reversal landscape. Additionally, it delves into the impact of structural properties of self-assembled nanochain clusters on the reversal behaviour. The findings offer valuable insights into fundamental magnetic phenomena in chemically synthesized magnetic nanostructures, emphasizing their morphological and geometric characteristics. This approach details minute features of nanostructures, paving the way for advancements in computer memory and biotechnology applications.

Periodic nano-structured superlattice with symmetry breaking along the surface as well as thickness is of high importance in plasmonic research due to its immense potential in bio-medical and environmental sensor applications. The structures are rich with electromagnetic hotspots and anisotropic optical properties contributing to the sensitivity of the device. In nanotechnology, nanosphere lithography (NSL) is a promising lithography technique that is in the limelight of research for the last decade due to its simplicity, scalability, and cost-effectiveness. Despite many advantages, the technique is limited in its versatility when it comes to real application. Conventional NSL offers less scope for structural variation with the most common six-fold symmetric structure as the nanosphere mask self-assembles in a hexagonal close-pack fashion due to the very nature of this process. Research efforts have been made to overcome the bottleneck. The conventional NSL approach is modified in combination with other techniques. In this chapter, we discuss the evolution of the NSL technique to achieve maturity. The chapter emphasizes modern NSL formalism associated with techniques like multistep shadow mask deposition and anisotropic etching to achieve 2D and 3D nanostructures with controlled shape, size, inter-structural gap, aspect ratio, sharpness, and special and vertical symmetry. The chapter will serve as an effective knowledge base for further research development in plasmonics, magnonics, and spintronics.

In this article, we present a systematic investigation on a multistep nanosphere lithography technique to uncover its potential in fabricating a wide range of two- and three-dimensional nanostructures. A tilted (polar angle) electron beam shower on a nanosphere mask results in an angled shadow mask deposition. The shape of the shadow also depends on the azimuthal angle of the mask sitting on top of the substrate. We performed angled shadow mask depositions with systematic variation of these two angular parameters, giving rise to complex nanostructures (down to 50 nm), repeated over a large area without defect. In this article, nanosphere lithography with two- and four-fold azimuthal symmetry was studied at constant tilt angles followed by variations in tilt without azimuthal rotation of the substrate. Finally, both angular parameters were simultaneously varied. The structure of shadow crystals was explained using Matlab simulation. This work stretches the horizons of nanosphere lithography, opening up new scopes in plasmonic and magnonic research.

The direct imaging of inhomogeneous current distribution was demonstrated by using the polar magneto-optical Kerr microscopy.

India is considered to have one of the maximum two wheeler density in the world. Hence, all the scooter and motorcycle manufacturers are striving to keep their market share by quickly bringing quality products with high mileage at a cheap price tag. As emission norms are becoming stringent day by day, these OEMs have to take care of every detail in the engine that is driving their vehicles. So today's engineers are obliged to refine and improve the technologies they use, faster and with greater accuracy than ever before.This paper focuses on reducing Cylinder Bore deformation for a two wheeler engine through CAE simulation. In standard testing conditions this deformation was observed to cause engine seizure. Bore deformation is of great significance to the overall performance of an engine. It can increase oil consumption, blowby and emissions and may influence piston dynamics to a great extent. These deformations are however, difficult to measure and being in micron level, are often prone to misinterpretation. Moreover, making physical prototypes with frequent design changes for reducing bore deformation is a highly time consuming and costly exercise since it involves most critical engine parts. These parts are often long lead time items in engine development cycle. This, with the added constraints on packaging and styling in two wheelers, leaves very little variations to be done on the design. Therefore, to cut down the design cycle time, virtual simulation methods are preferred.A high cubic capacity two wheeler gasoline engine is studied to evaluate and reduce deformation of cylinder liner. The cylinder head assembly comprising of major components like head, block, liner, etc. was meshed with second order elements and the analysis model was set up in a commercially available numerical code. The base design was then subjected to bolt pretension loads for simulating liner deformation. Based on this finite element analysis, the scope of reducing deformation was observed. Subsequently, a number of design modifications on liner, block and crankcases were made and thoroughly simulated under same loading conditions. This way a final proposal giving acceptable deformation was reached. The results of the final proposal, when compared to base design, indicated a useful reduction in deformation in the localized liner area without affecting stress and stiffness in other areas. The effect of modifying the cylinder head design on liner deformation was also studied. This paper may serve as a good reference for engineers who are targeting to reduce liner deformation in two wheeler engines.

Now a day’s automation is in every field, although there are many places automation has been emerged and successfully implemented but still the service provider for energy still uses conventional methods for getting the energy consumed by individual customer. This method is very time consuming and un- economical and may lead to human error. Our proposed system (AMR) will automatically send the data of the digital energy meter to the service provider with the help the help of the GSM modem once in a day and hence the system will report the service provider once in a through SMS. The same system can be used to check the last reading consumed by the consumer, when demanded by user through the same GSM modem .The device can also be used to control the load from both the ends that is (user –service provider) with the help of relay circuit and system will also be provided with an LCD display which will update the consumers with different information’s regarding tariff change or sudden power cut .