arXiv subjects

Suryakant Mishra

Publications and source records attributed to Suryakant Mishra.

8 recordsLinked to original sources

arXiv2026

Spin-Dependent Electron Transport through Bacterial Cell Surface Multiheme Electron Conduits

Multiheme cytochromes, located on the bacterial cell surface, function as long-distance (> 10 nm) electron conduits linking intracellular reactions to external surfaces. This extracellular electron transfer process, which allows microorganisms to gain energy by respiring solid redox-active minerals, also facilitates the wiring of cells to electrodes. While recent studies suggested that a chiral induced spin selectivity effect is linked to efficient electron transmission through biomolecules, this phenomenon has not been investigated in the extracellular electron conduits. Using magnetic conductive probe atomic force microscopy, Hall voltage measurements, and spin-dependent electrochemistry of the decaheme cytochromes MtrF and OmcA from the metal-reducing bacterium Shewanella oneidensis MR-1, we show that electron transport through these extracellular conduits is spin-selective. Our study has implications for understanding how spin-dependent interactions and magnetic fields may control electron transport across biotic-abiotic interfaces in both natural and biotechnological systems. Electron

physics.chem-ph↗

arXiv2025

Deep Generative Learning of Magnetic Frustration in Artificial Spin Ice from Magnetic Force Microscopy Images

Increasingly large datasets of microscopic images with atomic resolution facilitate the development of machine learning methods to identify and analyze subtle physical phenomena embedded within the images. In this work, microscopic images of honeycomb lattice spin-ice samples serve as datasets from which we automate the calculation of net magnetic moments and directional orientations of spin-ice configurations. In the first stage of our workflow, machine learning models are trained to accurately predict magnetic moments and directions within spin-ice structures. Variational Autoencoders (VAEs), an emergent unsupervised deep learning technique, are employed to generate high-quality synthetic magnetic force microscopy (MFM) images and extract latent feature representations, thereby reducing experimental and segmentation errors. The second stage of proposed methodology enables precise identification and prediction of frustrated vertices and nanomagnetic segments, effectively correlating structural and functional aspects of microscopic images. This facilitates the design of optimized spin-ice configurations with controlled frustration patterns, enabling potential on-demand synthesis.

cond-mat.dis-nn↗

arXiv2017

Generalization of Phonon Confinement Model for Interpretation of Raman Line-Shape from Nano-Silicon

A comparative analysis of two Raman line-shape functions has been carried out to validate the true representation of experimentally observed Raman scattering data for semiconducting nanomaterials. A modified form of already existing phonon confinement model incorporates two basic considerations, phonon momentum conservation and shift in zone centre phonon frequency. After incorporation of the above mentioned two factors, a rather symmetric Raman line-shape is generated which is in contrary to the usual asymmetric Raman line-shapes obtained from nanostructured semiconductor. By fitting an experimentally observed Raman scattering data from silicon nanostructures, prepared by metal induced etching, it can be established that the Raman line-shape obtained within the framework of phonon confinement model is a true representative Raman line-shape of sufficiently low dimensions semiconductors.

cond-mat.mes-hall↗

arXiv2017

Tent--Shaped Surface Morphologies of Silicon: Texturization by Metal Induced Etching

Nano--metal/semiconductor junction dependent porosification of silicon (Si) has been studied here. The silicon (Si) nanostructures (NS) have been textured on n-- and p-- type silicon wafers using Ag and Au metal nano particles induced chemical etching. The combinations of n--Si/Ag and p--Si/Au form ohmic contact and result in the same texturization on the Si surface on porosification where tent--shaped morphology has been observed consistently with n-- and p--type Si. Whereas, porosification result in different surface texturization for other two combinations (p--Si/Ag and n--Si/Au) where Schottkey contacts are formed. Quantitative analysis have been done using ImageJ to process the SEM images of SiNS, which confirms that the tent like SiNS are formed when etching of silicon wafer is done by AgNPs and AuNPs on n and p type Si wafer respectively. These easily prepared sharp tent--shaped Si NSs can be used for enhanced field emission applications.

cond-mat.mes-hall↗

arXiv2017

Three-fold Constructive Perturbation for Significant Enhancement in Field Emission from Nickel Oxide Nano-Thorn

A power efficient and stable field emission (FE) has been reported here from Nickel Oxide nanostructures. Modification in device geometry and surface micro- (nano-) structure has been found helpful in addressing the bottlenecks in achieving an efficient FE . In terms of threshold and turn on fields, three orders of magnitude better electron FE has been observed in the nickel oxide nanopetals (NiO-NPs) fabricated using simple hydrothermal technique. Uniform and vertically aligned NiO-NPs structures, grown on very flat conducting surface (FTO coated glass), show sharp needles like structures on the top edges of the flakes. These ultrafine structures play the main role in field emission to start at such a low turn on fields. The FE data (J-E plot) has been fitted with Fowler-Nordheim (FN) equation to estimate threshold field value and field enhancement factor which are found to be 3 V/mm and $\sim$ 5 $\times$ 10$^6$ respectively.

physics.app-ph↗

arXiv2016

In-situ spectroscopic studies of viologen based electrochromic device

Fabrication and operation of simple solid state electrochromic devices using ethyl viologen diperchlorate in a polymer matrix is presented here. In-situ Raman and transmission/absorption studies have been done to establish the origin of bias induced color change, between a transparent and navy blue color, in the electrochromic device. The origin of bias induced color change has been attributed to the bias induced redox switching between its viologen dication and free redicle forms. Fundamental reason behind colour changes of viologen molecule has been established. In-situ UV-Vis spectra reveals that the navy blue color of the device under biased condition is not due to increase in the transparency corresponding to blue wavelength but due to suppression of the transparency corresponding to the complementary colors. Absorption modulation has been reported from the device with good ON/OFF contrast of the device.

cond-mat.mes-hall↗

arXiv2016

Role of Metal Nanoparticles on porosification of silicon by metal induced etching (MIE)

Porosification of silicon (Si) by metal induced etching (MIE) process have been studies here to understand the etching mechanism. The etching mechanism has been discussed on the basis of electron transfer from Si to metal ion (Ag$^+$) and metal to H$_2$O$_2$. Role of silver nanoparticles (AgNPs) in the etching process has been investigated by studying the effect of AgNPs coverage on surface porosity. A quantitative analysis of SEM images, done using Image J, shows a direct correlation between AgNPs coverage and surface porosity after the porosification. Density of Si nanowires (NWs) also varies as a function of AgNPs fractional coverage which reasserts the fact that AgNPs governs the porosification process during MIE.

cond-mat.mes-hall↗

arXiv2015

Interplay between Phonon Confinement and Fano Effect on Raman line shape for semiconductor nanostructures: Analytical study

Theoretical Raman line shape functions have been studied to take care of quantum confinement effect and Fano effect individually and jointly. The characteristics of various Raman line shapes have been studied in terms of the broadening and asymmetry of Raman line shapes. It is shown that the asymmetry in the Raman line-shape function caused by these two effects individually does not add linearly to give asymmetry of line-shape generated by considering the combined effect. This indicates existence of interplay between the two effects. The origin of interplay lies in the fact that Fano effect itself depends on quantum confinement effect and in turn provides an asymmetry. This can not be explained by considering the two effects contribution independent of each other.

cond-mat.mes-hall↗