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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Start date: 2024

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Now showing 1 - 10 of 22
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    Design and Development of Mixed Perovskite Solar Cells with High Efficiency and Stability through DFT and AI-Based Design Approaches
    (University of North Bengal, 2025-03) Chatterjee, Suman; Subba, Subham; Talukdar, Avijit; Debnath, Pratik; Sarkar, Joy
    Compared to different solar technologies, Perovskite-based solar cells are preferred by many for their high PCE and cost-effectiveness. Still, building a market-ready solution requires handling various important issues related to stability, how the device is designed, and efficiency. The study presents comprehensive approaches involving Density Functional Theory (DFT), device modeling, and Machine Learning (ML) to improve and evaluate mixed perovskite materials. DFT was utilized to study the electronic structure, energy gap, and defect properties of perovskites. By using SCAPS-1D simulations, different optimization factors were studied. Furthermore, different ML algorithms were trained to find key device properties. The training involved both experiments and simulations to learn from the data and predict how each material would work, allowing for fast screening of various perovskite compositions. Because of this framework, researchers can identify new, efficient materials and learn more about how different compositions affect solar cell performance. This strategy uses DFT modeling, numerical simulation, and data analysis together to improve the speed of developing better perovskite solar cells.
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    Estimating Mass and Luminosity of Spectroscopic Binary Stars Using a Python-Based Computational Approach
    (University of North Bengal, 2025-03) Kundu, Jayashree; Mandal, Rakesh Kumar; Sarkar, Tamal
    Spectroscopic binary stars provide crucial insights into stellar masses, orbital dynamics, and evolutionary processes. This study presents a computational approach to analyzing spectroscopic binary systems using Python by developing an algorithm to estimate their mass and luminosity. In our study, the algorithm processes the spectral data, particularly variations in the Hydrogen-alpha line over time (in Modified Julian Date), to compute radial velocities by incorporating Doppler shifts and applying barycentric corrections. A sinusoidal function is then fitted to the velocity variations to determine the orbital period. The stellar masses are derived using the radial velocity curve with the inclination angle and orbital parameters. Given the mass-luminosity relation, the luminosities of the stars are estimated. Since the derived mass of the system ranges between 2 and 55 times the mass of the sun, the luminosity can be calculated based on the mass-luminosity relation, where luminosity is proportional to the stellar mass raised to the power of 3.5. This computational method offers an efficient and accurate technique for studying spectroscopic binaries, which can be extended to analyze large datasets from astronomical surveys, enhancing our understanding of binary star evolution.
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    Phase plane of a non-canonical scalar field model and cosmological consequences
    (University of North Bengal, 2025-03) Bhattacharya, Agnidipto; Biswas, Sujay Kr.
    This work deals with an investigation of phase plane analysis for a non-canonical scalar field in the background dynamics of spatially flat, homogeneous and isotropic Friedmann-Robertson-Walker (FRW) universe. Here, gravity is nonminimally coupled to scalar field having a real scalar field potential explicitly depending on cosmic time ‘t’. Nonlinear field equations are reduced to an autonomous system of ordinary differential equations by the suitable choice of dynamical variables. From the analysis of critical points, we have found the future decelerating phase of evolution of the universe.
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    Effect of Core and Its Position on the Properties of Fluorinated Nematic Liquid Crystals
    (University of North Bengal, 2025-03) Singha, Biplab Kumar; Debnath, Ashim; Haldar, Sripada
    Five nematic liquid crystal (NLC) compounds have been investigated by polarizing optical microscopy (POM), molecular mechanics and dielectric spectroscopy. Introduction of ethane (– CH2CH2–) bridge, its position, surrounding rings and fluorination were found to influence considerably molecular dipole moment (μ), inclination (β) i.e., frame of reference, dielectric anisotropy (Δε), threshold voltage (Vth), splay elastic constant (K11), relaxation time (τ ) and activation energy (Ea). It is observed that compounds show very lower melting and clearing temperatures. Nematic (N) phase stability is also found to be broader. All compounds show super cooling property near to room temperature except compound 3o2pp-f (N1). Splay elastic constant (K11), an important parameter is found to vary from 10−11 N to 10−10 N. Comparatively lower value of K11, lower value of restoring torque and alternatively faster response can be achieved. Undesirable energy absorption is found in between few hundred kHz to MHz region i.e flip-flop in nature.
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    Exploring AC Conductivity and Microstructure of Iron-Vanadium Doped Systems
    (University of North Bengal, 2025-03) Ghosh, Jiban; Bhattacharya, Sanjib
    The present work focuses on the impact of partial substitution of ZnO (former) by various other oxides in the microstructure and AC conductivity of newly developed amorphous semiconducting systems containing two transition metal ions such as vanadium and iron. The current materials may be significantly helpful in specialized applications like high-power lasers for their high refractive indices. An insightful study of the composition-dependent microstructure and electrical transport behavior with various former-modifier ratios is of great interest, not only from an application perspective but also for academic purposes.
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    Study of the mechanical properties of CdS2 and its enhanced optoelectronic performance under Mn doping: a first principles study
    (University of North Bengal, 2025-03) Thapa, Bhawana; Shankar, Amit
    Using density functional theory, a first-principles calculation was conducted to investigate the optoelectronic and mechanical properties of CdS2. The material exhibits semiconductor behavior with an indirect band gap of 1.3 eV under the GGA approach, which increases to 2.4 eV with mBJ correction. The pristine sample displays ductile characteristics and ionic bonding among its constituent atoms. Substituting Mn at the Cd site reduces the energy band gap while enhancing the material’s optical response. The pure CdS2 demonstrates favorable optical properties, including significant optical absorption, which is further improved by Mn doping. These features make CdS2 a promising candidate for optoelectronic applications such as photovoltaic devices, light emitters, and detectors.
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    Calorimetric study of an induced nematic to smectic A phase transition in a binary system of two smectogens: Existence of double tricritical points
    (University of North Bengal, 2025-03) Parvin, Apsari; Das, Malay Kumar
    In this work, we investigate a series of binary mixtures comprising two smectogenic compounds, 5DBT (containing terminal group, NCS and exhibiting smectic A1 phase) and 10OCB (having terminal group, CN and exhibiting smectic Ad phase). The binary system exhibits an induced N (nematic) phase within a definite concentration limit between X5DBT = 0.05 and X5DBT = 0.95. Utilizing high-resolution MDSC setup, we have carried out a detailed heat capacity measurement at the induced N to smectic A (SmA) transition. Analysis of the latent heat confirms the occurrence of two tricritical points: one having the McMillan ratio = 0.981 and the other corresponding to 0.983. A distinct pretransitional heat capacity change close to the transition temperature is observed. The renormalization group theory involving a correction-to-scaling factor, effectively describes this anomaly. The critical exponent α follows a distinct pattern when plotted against both mole fraction (X5DBT ) and McMillan ratio (TNA/TIN). As the system approaches the tricritical point (TCP), a consistent shift from 2nd order to 1st order N–SmA transition is noticed on each end of the phase diagram. Both the TCP shares a common McMillan ratio = 0.982. Additionally, the 3D–XY model is precisely attained near X5DBT = 0.687, corresponding to TNA/TIN = 0.909.
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    On maximum compactness bound in relativistic theory
    (University of North Bengal, 2025-03) Sharma, Ranjan
    This article reviews recent developments in estimating the maximum compactness bound of a compact star in the General Theory of Relativity and some extended theories of gravity.
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    Thermodynamic properties of the α-T3 quantum ring
    (University of North Bengal, 2025-03) Islam, Mijanur
    Here, we investigate the thermodynamic properties of an α-T3 quantum ring (QR) in presence of an external perpendicular magnetic field. We use coordinate transformation to describe the energy spectra of the quantum ring. In addition, we delve into the thermodynamic properties of the QR when it is exposed to a uniform magnetic field within a heat bath. To facilitate this, we employ the partition function obtained through the Euler-Maclaurin formula. In particular, we analyze the energy spectrum and the behaviour of fundamental thermodynamic functions in the canonical ensemble. These include the Helmholtz free energy, internal energy, entropy, and heat capacity. Notably, our study verifies the adherence to the Dulong-Petit law in both cases.
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    High-energy heavy-ion collision and quark-gluon plasma
    (University of North Bengal, 2025-03) Mali, Provash; Sarkar, Soumya; Mukhopadhyay, Amitabha
    Some basic aspects of quark-gluon plasma and relativistic nuclear collisions are reviewed. General features of heavy-ion collisions like their space-time evolution, the thermodynamics and hydrodynamics of the intermediate fireball created therein, the phase diagram of QCD matter, the signatures of QGP formation etc., are summarily discussed. We expect that this introductory review will be able to draw a general interest among the graduate students to a very exciting area of physics.