Department of Physics
Permanent URI for this communityhttps://ir.nbu.ac.in/handle/123456789/4173
Physics is one of those departments with which North Bengal University started its journey in the year 1962. At present there are nine faculty members and ten non-teaching employees in the department. The department has active research groups in the field of (a) Liquid Crystal, (b) Relativity, Cosmology, and Astrophysics, (c) High-energy Heavy-ion Interaction and Cosmic-ray Physics, and (d) Solid-state devices. Several research projects sponsored by the DST, DAE, UGC, and Tea Research Board are running in the department. In the year 2003 the department received a financial support under the FIST programme from the DST, Govt. of India. The department offers both M.Sc. and Ph.D. courses. A semester system is followed in the M.Sc. level, with three different areas of specialization namely, Condensed Matter Physics, Electronics and Nuclear and Particle Physics, out of which a student can choose one. The annual intake capacity in M.Sc. is 40 students. In the Ph.D. programme of the department right now 25 research students are enrolled under the supervision of different faculty members. Almost all faculty members are involved in intra and inter-university national and international collaborations of scientific research. The department houses one IUCAA Resource Centre, a Data Centre for Observational Astronomy, six teaching laboratories, several research laboratories and one departmental library. From time to time the department organizes Seminars, Symposia, Conferences, Schools, Refresher Courses, and Outreach Programs.
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Item Open Access Simulation Study of the Geomagnetic Influence on the EAS Muons(University of North Bengal, 2021-01) Basak, A.; Dey, R.K.The distribution of the muon content of highly inclined Monte Carlo cosmic ray showers is affected by the influence of Earth's geomagnetic field. It is found that the shapes of the positive and negative muon distributions get affected/ modified by the influence of the Earth's geomagnetic field. Such a correlation between the earth's geomagnetic activity and the cosmic ray (CR) air shower muons is found sensitive to the primary cosmic ray mass composition.Item Open Access Electronic Band Structure and Density of States Analysis of Electron Transport Materials for Perovskite Solar Cells(University of North Bengal, 2021-01) Sarkar, Joy; Biswas, Rajat; Chatterjee, SumanFor investigating the atomic-scale calculation of perovskite solar cells (PSCs), a detailed model of interaction between the electrons and the junctions is very essential. Such atomicscale level analysis is based on the quantum mechanical model. Therefore we need a Schrödinger equation which involves all the electrons with the associated junction potential. Here we consider the Schrödinger equation and solving it by full-potential linearized augmented plane wave (LAPW) method in Wien2k code through the Density Functional Theory (DFT). We have used generalized gradient approximation (GGA) given by Perdew-Burke-Ernzerhof (PBE) for the electronic band structure and Density of States (DOS) calculation of TiO2 and ZnO which are used in perovskite solar cell as the electron transport layer. We obtained the value of the energy bandgap as ~2.934 eV for TiO2 and ~3.119 eV For ZnO. We also determined the value of Fermi energy for both of the material. Finally, we compare the transport properties of TiO2 and ZnO by analyzing their band structure and DOS diagrams.Item Open Access Improvement of Photovoltaic Performance of Dye Sensitized Solar Cells by Pre-Dye Treating of Zno Nanoparticles(University of North Bengal, 2021-01) Biswas, Rajat; Sarkar, Joy; Chatterjee, SumanDye sensitized solar cells (DSSC) were fabricated using Rose Bengal dye. Pure and pre-dye treated Zinc oxide (ZnO) nanoparticles were used to fabricate the photoanodes of two cells. The structural characteristics of ZnO nanoparticles were studied using X-ray diffraction analysis and the surface morphology by Scanning electron microscopy. The absorption property of the dye was studied using UV-VIS spectra. The pre-dye treatment has improved the properties of ZnO, such as reduced agglomeration, improved morphology, increased dye adsorption and reduced dye aggregation. Photovoltaic parameters like short circuit current density (JSC), open circuit voltage (VOC), fill factor (FF) and overall energy conversion efficiencies (η) for the conventional and pre-dye treated ZnO based fabricated cells were calculated to be 3.73 mA/cm2, 0.53 V, 0.63 and 1.26 % and 4.47 mA/cm2, 0.55 V, 0.62 and respectively. The pre-dye treated DSSC showed an improvement in short circuit current density (Jsc) by 19.84% and efficiency (η) by 21.43 %.Item Open Access Effect of Bias on The Solar Cell Characteristics(University of North Bengal, 2021-01) Debnath, Pratik; Chatterjee, SumanConsiderable attention was created over the past decade on Dye-sensitized solar cells (DSSCs) as a viable alternate technology for renewable energy. Much attention was attracted due to their high efficiencies and potentially low production costs. In this paper, Dye-sensitized solar cells with natural dyes were successfully synthesized using ZnO nanostructures. ZnO nanorods were grown on an ITO coated glass using sol-gel method and used to fabricate DSSCs using natural dyes and liquid Potassium Iodide electrolyte. Different natural dye were analyzed for its suitability to be used in DSSC and subsequently used to fabricate the cell. Finally the photovoltaic properties of the ZnO based DSSC samples were systematically analyzed. Roles of new sensitizer dye were investigated and the results were compared. The ZnO nanorods grown by the sol-gel method have more uniform thickness. The DSSC structure with Carbon counter electrode yields an open circuit voltage markedly higher from DSSC on an ITO glass and has energy conversion efficiency less than 2%.Item Open Access Spectral and Timing Analysis of Radio Quiet X-Ray source 1E 161348-5055.1 using XMM Newton Mission(University of North Bengal, 2021-01) Sarkar, TamalNeutron stars are remnants of supernovae explosion of massive stars upto 20-40 Mʘ at the time of their formation, neutron stars gain recoil kicks due to asymmetries that develops during the core-collapse process. Neutron stars are classified as Radio Loud and Radio Quiet. 1E 161348-5055.1 is a radio quiet neutron star found in the Centre of RCW103 which is Supernova Remnant (SNR) and is a periodic X-Ray with a period of 6.67 hours. This source was discovered by the HEAO-2 (Einstein Observatory), which is the first fully imaging XRay telescope. This source attracted interest due to the two main reasons. Firstly, its periodicity of 6.67 hrs which is too long for star having age 2000 years, it is behaving like a multi-million-year-old star. Secondly, the star becomes 50 times brighter in between October 1999 and January 2000. Astrophysicist put forward many theories to explain this phenomenon. In present work, the author downloaded one archived data from XMM Newton Mission and analyzed it as well as reviewed the works related to this source to understand the nature of the neutron star 1E 161348-5055.1.Item Open Access Array Of Nanostructured Sensor Elements For Determination of Tea Quality(University of North Bengal, 2021-01) Ghosh, Aparna; Roy, Chinmay; Chatterjee, SumanDetection of Volatile organic compounds is important for identification of flavour in different commercial organic products like Tea, Coffee, Wine, etc. The flavour components are detected through porous nanostructured Zinc Oxide (ZnO) sensing elements. This work shows the potential application of nanostructured gas sensor arrays for monitoring the quality of Indian tea.Item Open Access Study of DSSC dye using density functional theory(University of North Bengal, 2021-01) Talukdar, Avijit; Chatterjee, SumanThe abstract should be one paragraph of between 150 and 250 words. It is not indented. Section titles, such as the word Abstract above, are not considered headings so they don’t use bold heading format. Instead, use the Section Title style. This style automatically starts your section on a new page, so you don’t have to add page breaks. (To see your document with pagination, on the View tab, click Reading View.) Note that all text styles for this template are available on the Home tab of the ribbon, in the Styles gallery.Item Open Access Investigation of Oxygen Sensing Capabilities and Relative Performance of Commonly Used Materials in A Combustion Environment(University of North Bengal, 2021-01) Roy, Chinmay; Chatterjee, SumanSeveral different oxygen sensitive materials have been synthesized and relative sensing capability was evaluated. Resistive response behaviors with varying oxygen gas concentration on TiO2, Nb2O5, WO3, La2CuO4, SrTiO3, SrCeO3 and La0.8Sr0.2MnO3 have been studied. The best operating temperature for maximum sensitivity was identified individually. The response at optimum temperature was calibrated for actual lean and rich combustion environment. The relative sensitivities with all pollutant gases present in combustion exhaust have been investigated in their relative concentration ranges.Item Open Access Relativistic compact stellar model describing anisotropic stars(University of North Bengal, 2021-02) Baskey, Lipi; Das, ShyamIn this paper, we have derived a class of analytical solutions of Einstein field equations for a spherically symmetric anisotropic matter distribution. By choosing one of the metric potentials grr to be Krori-Barua metric type and a specific choice of anisotropy we obtain the other metric function. The interior solutions thus obtained has been utilized to construct a potentially stable model that could describe compact stellar objects. The exterior vacuum region has been assigned with the Schwarzschild spacetime metric. Across the boundary of the compact star where the radial pressure drops to zero, the interior metric has been matched smoothly with the exterior metric to fix the model parameters associated with the solutions. All the regularity conditions, energy conditions and all other physical requirements demanded for a realistic compact system has been shown to satisfy graphically with this model corresponding to the pulsars 4U1820 - 30 (Mass= l.58M0 and radius= 9.1 km) [1] and Gen X - 3 (Mass= l.49M0 and radius= 10.136 km)[2]. The stability of the model is also discussed using some of the known stability criterion namely TOV equation, adiabatic index, Buchdahl condition and Herrera's cracking concept etc. The wide applicability of our developed model has been justified with the numerical values of current observational data set from various other known compact stars to a high degree of accuracy.Item Open Access TeV-PeV energy neutrinos and gamma rays from extragalactic milli-second pulsars(University of North Bengal, 2021-03) Dey, Rajat; Sarkar, TamaiThe origin of the detected diffuse flux of extragalactic Pe V neutrinos during 2010 - 2017 by the Ice Cube Experiment is not clear and various models with sources were proposed for it. In the present work, we try to find theoretically whether pulsars could be one possible source. With our study, we found that the extragalactic millisecond pulsars which are newly born may be one possible source of Pe V neutrinos and gamma rays. For the purpose, we took two-step particle acceleration scheme for transferring the rotational energy to the electrons which are accelerated to high energy or boosted up to ~ 0.01 EeV energies or above. The high energy boosted electrons interacted with cold positrons and soft radiation in the acceleration zone might produce Ultra High Energy (UHE) neutrinos and gamma rays. The theoretically derived extragalactic muon neutrino energies are found consistent with the Ice Cube detection.Item Open Access Brief overview of Nanomechanical Qubits(University of North Bengal, 2024-03) Samanta, ChandanQubits are the building blocks for quantum computers and quantum information processing. However, there is a great deal of dispute over the most ideal types of qubits. The nanomechanical qubit might be one potential addition to the qubit platforms. Here, we briefly outline the underlying physical principle of a nanomechanical qubit, where the mechanical vibrations stores the informationItem Open Access Short course on the Su-Schrieffer-Heeger model(University of North Bengal, 2024-03) Ghosh, Tarun KantiReview various topological properties of a dimer Su-Schrieffer-Heeger tight-binding model. Exact analytical expressions of the energy spectrum and corresponding eigenstates for any choice of system parameters are provided. We discuss the system’s parity, time-reversal, and chiral symmetries. The system undergoes a topological phase transition while tuning the hopping parameters. The topological phase is associated with the presence of the boundary modes and establishes the bulk-boundary correspondence.Item Open Access Na2O Doped Solid State Battery Electrolytes: Preparation and Electrical Characterization(University of North Bengal, 2024-03) Ram, Rakesh; Bhattacharya, SanjibNa2O doped glassy electrolytes have been developed to explore their electrical transport behaviour at ambient temperature. The electrical conductivity (mixed conduction) has been studied in the light of both frequency as well as temperature. In the low frequency range, the diffusional motion of Na+ ions is expected to be the possible reason for a flat conductivity. It is also noted that the conductivity shows dispersion near the high frequency regime. The DC conductivity ( dc) and hopping frequency have been extracted from the best fitted plots of experimental data. The thermally active nature of electrical conductivity data have been studied to establish the dynamics of charge carriers via hopping conduction in sodium oxide glassy systems. Negligible small difference in pathways in the I-V characteristics in both the directions should make a sense for their applications for new generation battery-electrolyte.Item Open Access Method of estimating the EAS cores of Monte Carlo showers for the GRAPES-3 experiment(University of North Bengal, 2024-03) Basak, AnimeshProcedure of estimating the different extensive air shower (EAS) parameters is inherently linked to the accurate estimation of the cosmic-ray EAS cores. In EAS data analyses, the core of an EAS is estimated simultaneously with other crucial EAS parameters like shower size, shower age, etc. by fitting the lateral density data (LDD) of either the EAS charged secondaries or purely electrons with some suitably chosen lateral density function employing the maximum likelihood method. The present analysis estimates EAS cores using the LDD of electrons that fall on the scattered array detectors from the simulated EASs initiated by proton and iron primaries. Considering a densely packed detector array, including configurations akin to GRAPES-3, the research employs a straightforward weight average method (WAM) for the EAS core estimation. The findings reveal that around 95.5% of simulated showers exhibit EAS cores within a deviation range of approximately 1 m to 3 m from the actual cores of the CORSIKA Monte Carlo showers initiated by proton and iron primaries.Item Open Access Spin and valley dependent transport in a biased dice lattice(University of North Bengal, 2024-03) Tamang, LakpaWe study the spin and valley-dependent transport in a spin-orbit coupled biased dice lattice. We find that the presence of a bias term and the spin-orbit interaction (SOI) give rise to the spin-split energy spectrum. The SOI couples the valley and the spin degrees of freedom, resulting in a spin and valley-resolved Berry curvature. We find a profound variation in the Berry curvature for different spin states around both valleys. The spin and valley Hall conductivities are calculated for various values of the bias term. We find the interplay between the bias term and SOI term leads to a quantum phase transition from a topological insulating phase to a trivial band insulating phase accompanied by the emergence of the valley Hall effect and the suppression of the spin Hall effect.Item Open Access Recent Efforts Towards Understanding the Early Universe from a Fundamental Quantum Perspective(University of North Bengal, 2024-03) Modak, Sujoy K.Observable universe is fundamentally inhomogeneous and anisotropic. Quantum description of the generation of these inhomogeneities and anisotropies is ill-understood and unsatisfactory. After providing a brief account of the standard approach of the generation of the classical density perturbations starting from the quantum fluctuations of inflaton field, I critically review various assumptions which are crucial for the success of this description, and point out various shortcomings around it. I also discuss the basic ideas and recent works by using an alternative path to overcome those shortcomings which is motivated by the so-called Collapse Model interpretation of quantum mechanics. Inspired by these works, I argue the necessity of constructing a class of manifestly inhomogeneous and anisotropic quantum states after inflation and discuss my recent works which provide one such prescription of building such a state, called the T-vacuum, defined in the radiation dominated stage of the early universe.Item Open Access Spectral variability in the orbital profiles of TeV Binary LSI + 61o 303 in X-Ray window using XMM - Newton Observations(University of North Bengal, 2024-03) Sarkar, TamalLSI + 61o 303 is a high-mass X-ray binary consisting of a low-mass [M (1 - 4)M ] compact object orbiting around an early type B0 Ve star along an eccentric e = 0:7 orbit. It along with LS5039 are the only two known gamma-ray binary detected in the TeV band. Despite extensive observations the nature of this source, particularly whether it is a pulsar or a black hole (microquasar) system, is not clear. The mechanisms that lead to the multi-wavelength behavior are also uncertain. Recent approach to the study of LSI + 61o 303 has been to focus on possible correlated variability. There was an early indication that there is a correlation between the X-ray and TeV emission at the time where the latter was measurable. In a more recent observation, however, such a feature has not been found. In this work, we study the spectral variability of LSI + 61o 303 using four observations between 2001 to 2007 of XMM - Newton available from NASA archive and examine the correlation between low energy range and high energy part.Item Open Access Flexible Piezoelectric Energy Harvester Based on UV Light Emitting Ce3+-Complex-P(VDF-HFP) Composite Films(University of North Bengal, 2024-03) Barman, Priti Sundar; Adhikary, PrakritiIn this study, we report on the preparation of a polymer composite film with enhanced ( 99%) electroactive phases - and -phase) based on P(VDF-HFP) copolymer and Ce3+-complex. Furthermore, its utilization in piezoelectric-based flexible energy harvesting (PFEH) device fabrication has been studied, where the electrostatic interactions between the surface charges of Ce3+-complex and -CH2-/-CF2- molecular dipoles of P(VDF-HFP) via H-bonding co-operate to stabilize the electroactive phases and enhance its piezoelectric properties. PFEH generates 3 V of open circuit voltage and 0.16 A short-circuit current under the external pressure impacting amplitude of 14.20 kPa. Moreover, it can successfully charge up capacitor by repeating finger impact which indicates its potency as an efficient energy-harvesting device. Besides this, the composite film exhibits an intense photoluminescence in the UV-region that might be very promising in the area of high-performance, energy-saving, flexible, solid-state UV light emitters and fabrication of hybrid multifunctional energy harvester where mechano-luminescence phenomenon might be possible to include.Item Open Access Prediction of Cross Port Output in Electro-optic Mach-Zehnder interferometer Using Artificial Neural Network(University of North Bengal, 2024-03) Gayen, Dilip Kumar; Chattopadhyay, TanayArtificial neural networks are essential for the design and analysis of complex algorithms. We have designed a circuit with an electro-optic Mach-Zehnder interferometer (EOMZI) driven by a photodiode. The output from the EOMZI’s cross bar port is used. Then, we have developed a photonic artificial neuron based on this setup. The outputs are validated using MATLAB, and the Artificial neural networks successfully generate the sigmoid function corresponding to the EOMZI switch’s cross port.Item Open Access Variable thermoelectric parameters in Si / Ge zNR by electrostrictive application of localized strain(University of North Bengal, 2024-03) Sengupta, AmretashisIn this work, we propose the tuning of thermoelectric performance of zigzag monolayer Silicene and Germanene nanoribbon (SiNR/GeNR) with a reversible strain engineering method. By a proposed electrostrictive method a tensile or compressive moderate strain of ±2% orthogonal to the transport direction in a short region of the SiNR or GeNR is considered to be applied. A selfconsistent density functional tight binding (DFTB) approach is employed for the calculation of the electronic properties of the system, while the vibrational properties are computed with classical molecular dynamics simulations. Electron/phonon transport is computed with the Green’s function formalism. With the localized strain application it is observed that electron transmission and current through the Si or GeNR remains largely unaffected while a suppression of the phonon transport and thermal conductance can be achieved. A significant tuning is observed for thermoelectric figure of merit and variations are seen in the Seebeck coefficient and the thermoelectric power factor. Moreover the temperature and doping dependencies of these parameters also showed high degree of tunability with strain. The enhancements in thermoelectric figure of merit by such simple strain ON/OFF mechanism in a CMOS compatible architecture suggest good prospects for nanoscale thermoelectrics.