Indian Journal of Physics最新文献

{"title":"Physical acceptability of modified Rényi holographic dark energy cosmological model in ({varvec{f}}left( {{varvec{T}},user2{mathcal{B}}} right)) theory of gravitation","authors":"V. A. Thakre,&nbsp;R. G. Kandarkar,&nbsp;A. K. Dabre","doi":"10.1007/s12648-026-04132-2","DOIUrl":"10.1007/s12648-026-04132-2","url":null,"abstract":"<div><p>In this study, we consider a modified dark energy model in the framework of <span>(fleft( {T,;mathcal{B}} right))</span> gravity theory, where <i>T</i> is the torsion scalar, and <span>(mathcal{B})</span> is the boundary term of spacetime. The model we consider is the LRS Bianchi type-I spacetime in the presence of modified Rényi holographic dark energy and pressureless matter. To solve the field equations and obtain a deterministic solution, we contemplate the simple form of <span>(fleft( {T, ;mathcal{B}} right))</span> gravity as <span>(fleft( {T,mathcal{B}} right) = alpha mathcal{B}^{beta } + T)</span> and the emergent scale factor. We calculated the cosmological parameters to study the behaviour of the Universe during cosmic evolution. The reconstructed dark energy sector has been compared with observations of BAO, SNe, and certain galaxy lensing, as well as Planck-based <span>({Lambda })</span>CDM measurements.</p></div>","PeriodicalId":584,"journal":{"name":"Indian Journal of Physics","volume":"100 11","pages":"4961 - 4978"},"PeriodicalIF":1.7,"publicationDate":"2026-09-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://link.springer.com/content/pdf/10.1007/s12648-026-04132-2.pdf","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"149163092","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Integration of experimental and simulation approaches to optimize CdS buffer layers in CZTS based heterojunction solar cells","authors":"Ronaldo Roy,&nbsp;K. Kathir,&nbsp;M. C. Santhosh Kumar","doi":"10.1007/s12648-026-04127-z","DOIUrl":"10.1007/s12648-026-04127-z","url":null,"abstract":"<div><p>An integrated approach of experimentation and numerical simulation were employed to investigate the influence of cadmium sulfide (CdS) buffer layer on the performance of CZTS based heterojunction solar cells. The effect of variation in deposition time with the properties of CdS and its role as the n-layer in CdS/CZTS devices has been investigated. The deposition time of CdS thin films were varied from 30 to 120 min using a cost-effective chemical bath deposition. To investigate properties of the films XRD, SEM, EDS, Raman, and UV–visible characterisations were carried. XRD analysis confirmed the presence of cubic-phase CdS with improved crystallinity, while SEM images showed a densely packed, boulder-like morphology. Additionally, EDS confirmed a stoichiometric Cd-to-S ratio. Film thickness found to increase from 160 to 400 nm, while bandgap slightly narrowed from 2.46 to 2.40 eV. Hall measurement showed improved n-type conductivity with deposition time. Heterojunctions devices of architecture &lt; FTO/CdS/CZTS/Ag &gt; were fabricated and their junction parameters are evaluated by using I-V measurements. Further, solar cell devices of the same structure were simulated using SCAPS-1D. The CdS layer deposited for 30 min yielded the best performance, with a simulated efficiency of 17%. This investigation suggests that deposition time of CdS film is a key parameter for optimizing photovoltaic devices.</p></div>","PeriodicalId":584,"journal":{"name":"Indian Journal of Physics","volume":"100 11","pages":"4769 - 4781"},"PeriodicalIF":1.7,"publicationDate":"2026-09-03","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"149163091","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Influence of nonlinear conventional saturation on spatio-temporal modulational instabilities in PT-symmetric fiber Bragg grating structures","authors":"P. Mohanraj,&nbsp;R. Sivakumar,&nbsp;Ancemma Joseph,&nbsp;B. Felcia Merlin,&nbsp;Mohd. Shkir","doi":"10.1007/s12648-026-04177-3","DOIUrl":"10.1007/s12648-026-04177-3","url":null,"abstract":"<div><p>This paper is intended to present an investigation into the impact of cubic, quintic, and saturable nonlinearity on the instability in PT-symmetric fiber Bragg grating structures (FBG) with various PT-symmetry regimes. A conventional linear stability analysis identifies the modulational instability (MI) gain, where the combinatorial influence of cubic and quintic nonlinearities on MI is carefully studied in both normal and anomalous dispersion regimes. Additionally, we investigate the characteristics of MI at the bottom and top edges of the photonic band gap. The investigation highlights the importance of non-Kerr nonlinearity in relation to the MI gain. It is shown that even in the presence of PT-symmetry, one could effectively control the MI by varying the cubic, quintic, and saturable nonlinearity for various PT-symmetric regimes. The investigation revealed a range of spectral varieties, including asymmetry, symmetry, sideband spectrum, steadily increasing gain, broad spectrum, and others. We find an anomalous spectrum that is more discrete than continuous for the few physical components. The emergence of solitary waves in nonlinear episodic structures is also examined following the use of PT-symmetry.</p></div>","PeriodicalId":584,"journal":{"name":"Indian Journal of Physics","volume":"100 10","pages":"4353 - 4369"},"PeriodicalIF":1.7,"publicationDate":"2026-08-29","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"148909655","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Analytic fill factor expression for double junction tandem solar cells","authors":"Neda Hasanzadeh Bishegahi,&nbsp;Abdollah Eskandarian,&nbsp;Abbas Ghadimi,&nbsp;Ali Esmaeeli","doi":"10.1007/s12648-026-04154-w","DOIUrl":"10.1007/s12648-026-04154-w","url":null,"abstract":"<div><p>We present closed form analytic formulae for the fill factor of single and double junction tandem solar cells. We start with the observation that the difference between maximum power voltage and open circuit voltage is small compared to their values. Then an explicit relation relating the maximum power voltage to the open circuit voltage is derived for the single junction (SJ) cell. Consequently, fill factor (FF) is expressed solely as a function of the open circuit voltage. Our expressions are examined against those given in literature for the SJ cell and show very good agreement. Comparing the results of our calculations against data points given in literature, the ideality factor is varied as a parameter and cumulative error is calculated. Satisfactory agreement is observed for Silicon cells with n = 1.1 and III-V compound cells with n = 1.7. The SJ derivation validates our approach which is also applied to the double junction (DJ) cells. Clearly, the complexity is increased for the DJs. Additional factors such as the photo current ratio of the sub cells enters the equations. Nevertheless, closed form expression is obtained for the FF in terms of the open circuit voltage. The prediction of our double junction formula is compared with the data points quoted in literature with ideality factor as a parameter and good agreement is obtained with n = 1.8 assuming sub-cell photo current ratio of 2:1. Having established the above parameters, our calculations are within 10% of the results quoted in literature. In fact, the agreement is better than 5% for near 90% of the cases considered.</p></div>","PeriodicalId":584,"journal":{"name":"Indian Journal of Physics","volume":"100 10","pages":"4271 - 4284"},"PeriodicalIF":1.7,"publicationDate":"2026-08-22","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"148909812","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Uncertainty-aware physics-informed machine learning for non-equilibrium heat transport in casson fluid","authors":"Smile Bansal,&nbsp;Krrish Punj,&nbsp;Mamta Gulati,&nbsp;Sapna Sharma","doi":"10.1007/s12648-026-04134-0","DOIUrl":"10.1007/s12648-026-04134-0","url":null,"abstract":"<div><p>The current study provides a comprehensive analysis of heat transfer in porous media within the framework of local thermal non-equilibrium (LTNE). It takes into account the combined effects of non-Newtonian Casson fluid behavior, spatially varying Biot number, and temperature-dependent thermal conductivities. The simultaneous consideration of these interacting factors poses significant analytical and numerical complexities, particularly when extending the formulation to more complex geometries or thermal behavior. To effectively solve the resulting nonlinear and coupled system of differential equations, we employ Physics-Informed Neural Networks (PINNs), ensuring high accuracy and efficiency. The PINN framework integrates the governing equations and associated boundary conditions directly into the neural network training process, enabling effective handling of nonlinearities and spatial variations. The accuracy of the PINN approach is validated through comparison with solutions obtained from MATLAB’s bvp4c solver, especially for cases where the spatially varying Biot number profiles presented significant training difficulties. Parametric studies demonstrate the significant influence of fluid rheology, spatially varying Biot number, and nonlinear thermal conductivity on heat transfer characteristics within the porous media. Additionally, to quantify epistemic uncertainty in predictions, arising from model formulation, numerical approximation, and learning dynamics, Monte Carlo dropout is employed during inference, enabling estimation of a 95% confidence interval and thereby enhancing the reliability of our results. The outcomes highlight the potential of PINNs as powerful computational tools for tackling complex multiphysics problems involving LTNE models.</p></div>","PeriodicalId":584,"journal":{"name":"Indian Journal of Physics","volume":"100 11","pages":"4871 - 4892"},"PeriodicalIF":1.7,"publicationDate":"2026-08-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"149163155","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Unveiling the versatile characteristics of lead-free K2CuSbCl6 double perovskite for advanced optoelectronic applications","authors":"Tanvir Al Galib,&nbsp;Md. Faruk Hossain,&nbsp;Md Masum Mia,&nbsp;Mongi Amami,&nbsp;Lamia Ben Farhat,&nbsp;Abdullah Marzouq Alharbi,&nbsp;Noureddine Elboughdiri,&nbsp;Md. Ferdous Rahman","doi":"10.1007/s12648-026-04130-4","DOIUrl":"10.1007/s12648-026-04130-4","url":null,"abstract":"<div><p>Lead-free halide double perovskites are attracting significant attention as environmentally benign alternatives to conventional Pb-based perovskites for advanced optoelectronic and photovoltaic applications. In this study, the structural, electronic, mechanical, and optical properties of the inorganic cubic double perovskite K₂CuSbCl₆ were systematically investigated using density functional theory (DFT) within the CASTEP package. The optimized crystal structure exhibits excellent thermodynamic and structural stability, evidenced by negative formation energy of − 3.23 eV/atom and a Goldschmidt tolerance factor of 0.98. Dynamical stability was further confirmed through phonon dispersion calculations, which showed no imaginary phonon modes. Electronic structure analysis identifies K₂CuSbCl₆ as an indirect-bandgap semiconductor with bandgaps of 0.655 eV (GGA-PBE), 0.45 eV (GGA-PBE + SOC), and 0.93 eV (HSE06). The valence band is primarily composed of Cu-d and Cl-p hybridized orbitals, while Sb-p states dominate the conduction band. Elastic calculations satisfy the Born stability criteria, revealing a mechanically stable, ductile, and anisotropic material with a Pugh’s ratio of 3.42 and a Poisson’s ratio of 0.366. Optical analysis demonstrates strong visible-to-near-infrared absorption, a static dielectric constant of 6.54, and a refractive index of 2.55, indicating efficient light-harvesting capability. These findings establish K₂CuSbCl₆ as a promising lead-free material for sustainable photovoltaic and optoelectronic devices.</p></div>","PeriodicalId":584,"journal":{"name":"Indian Journal of Physics","volume":"100 11","pages":"4783 - 4797"},"PeriodicalIF":1.7,"publicationDate":"2026-08-06","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"149163153","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Structural and optical properties of BaAl2O4: Eu2+ nanophosphor","authors":"V. T. Jisha,&nbsp;D. G. Aswathy,&nbsp;R. Meenakshi","doi":"10.1007/s12648-026-04123-3","DOIUrl":"10.1007/s12648-026-04123-3","url":null,"abstract":"<div><p>Europium (Eu²⁺)-doped barium aluminate (BaAl₂O₄) nanophosphor was successfully prepared via the sol–gel route. X-ray diffraction analysis confirmed the hexagonal BaAl₂O₄ structure with an average crystallite size of 20 nm. SEM analysis revealed irregularly shaped, closely packed grains with slightly rough surfaces, indicating partial agglomeration of nanoparticles. The UV–Visible absorption spectrum demonstrated a broad absorption peak in the UV region, attributed to O²⁻ → Eu²⁺, confirming the effective incorporation of Eu²⁺ ions into the BaAl₂O₄ host lattice. Upon 397 nm excitation, the photoluminescence spectrum shows a broad, intense blue-green emission peak at 495 nm. This strong emission peak around the visible region was attributed to parity-allowed transition 4f⁶ 5d¹ → 4f^{7 8}S_7/2, which is highly sensitive to the crystal-field environment of the host lattice. The broad emission profile suggests efficient energy transfer and strong interaction between Eu²⁺ ions and the BaAl₂O₄ matrix. The observed intense luminescence and structural stability demonstrated that Eu²⁺-doped BaAl₂O₄ nanophosphor is a prominent material for solid-state lighting and persistent luminescent applications.</p></div>","PeriodicalId":584,"journal":{"name":"Indian Journal of Physics","volume":"100 11","pages":"4729 - 4736"},"PeriodicalIF":1.7,"publicationDate":"2026-07-27","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"149162899","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"First-principles investigation of structural, electronic, magnetic, mechanical and thermoelectric properties of PdFeMn1−xScxSi Heusler alloys for thermo-spintronic applications","authors":"Rachida Temzini,&nbsp;Yahia Bourourou,&nbsp;Hichem Boulebda,&nbsp;El Tayeb Bentria","doi":"10.1007/s12648-026-04118-0","DOIUrl":"10.1007/s12648-026-04118-0","url":null,"abstract":"<div><p>The integration of spin-polarized transport with efficient thermal energy conversion is a key objective in the development of next-generation multifunctional materials. In this work, first-principles calculations based on density functional theory are employed to investigate the tunable thermo-spintronic properties of the quaternary Heusler alloys PdFeMn_1−xSc_xSi (x = 0, 0.25, 0.5, 0.75, and 1). The results confirm that all compounds are energetically, thermodynamically, and dynamically stable in the ferromagnetic configuration. Electronic structure analysis reveals half-metallic behavior for compositions with x ≤ 0.75, with a maximum spin-down band gap of about 0.18 eV, while the x = 1 compound exhibits a nearly half-metallic character. The total magnetic moment follows the Slater–Pauling rule, decreasing from 5 to 1 μB with increasing Sc content. The Curie temperatures reach values as high as 851 K, indicating strong ferromagnetic stability. Furthermore, the investigated alloys exhibit promising thermoelectric performance, with Seebeck coefficients up to 407 μV K⁻¹ and low lattice thermal conductivity (~ 0.49 W m⁻¹ K⁻¹), with a maximum figure of merit of 0.88 at 300 K. These findings suggest that PdFeMn_1−x Sc_xSi alloys are promising candidates for energy conversion and thermo-spintronic applications.</p></div>","PeriodicalId":584,"journal":{"name":"Indian Journal of Physics","volume":"100 11","pages":"4703 - 4727"},"PeriodicalIF":1.7,"publicationDate":"2026-07-27","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"149163132","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Atomic-scale mechanisms of electromigration resistance in thickness-dependent micro-bump interconnects","authors":"Hsien-Chie Cheng,&nbsp;Ching-Feng Yu","doi":"10.1007/s12648-026-04141-1","DOIUrl":"10.1007/s12648-026-04141-1","url":null,"abstract":"<div><p>This study presents a rigorous quantum–mechanical evaluation of the electromigration resistance inherent to Sn-3.5Ag/Cu₃Sn/Cu/Ni and Sn-3.5Ag/Cu₆Sn₅/Cu/Ni micro-bump interconnect architectures subjected to applied electric fields of 0.05 V/Å and 0.1 V/Å. By employing first-principles density functional theory, this investigation quantitatively elucidates the average bond lengths and interfacial adhesion strengths across critical metallurgical boundaries. Specifically, it targets the junctions bridging the solder bump with the copper-tin intermetallic compounds (IMCs), as well as the interfaces separating these IMCs from the under-bump metallurgy (UBM). Furthermore, the research systematically delineates how thickness variations within the Cu₃Sn and Cu₆Sn₅ intermetallic layers modulate intrinsic interfacial bonding characteristics. Computational simulations reveal that structural degradation and interfacial failure preferentially initiate at the boundary bridging the solder bump and the underlying intermetallic layer. Notably, the atomistically predicted interfacial adhesion strength exhibits a monotonic degradation in response to escalating electric field intensities. Moreover, structural analysis indicates that the boundary between the intermetallic layer and the UBM possesses a fundamentally lower thermodynamic adhesion capacity than the solder-intermetallic junction, thereby rendering it highly vulnerable to electromigration-induced cleavage. Consequently, theoretical findings determine that the progressive thickening of copper-tin intermetallic layers compromises the overall electromigration resistance of micro-bump interconnects. Significantly, this theoretical framework establishes a robust atomic-scale understanding of the localized degradation mechanisms that dictate interconnect reliability. These fundamental insights provide vital predictive design paradigms for optimizing interfacial stability and maximizing the operational endurance of next-generation, high-density three-dimensional integrated circuit packaging platforms.</p></div>","PeriodicalId":584,"journal":{"name":"Indian Journal of Physics","volume":"100 11","pages":"4541 - 4551"},"PeriodicalIF":1.7,"publicationDate":"2026-07-22","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"149163057","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Effects of electromagnetic ion cyclotron wave-particle interactions on ion velocity distribution functions in the Earth’s magnetosphere: MMS observations","authors":"M. S. Hussain,&nbsp;C. Shen,&nbsp;A. A. Abid,&nbsp;N. Ahmad,&nbsp;S. Ali,&nbsp;M. N. S. Qureshi,&nbsp;A. Esmaeili","doi":"10.1007/s12648-026-04125-1","DOIUrl":"10.1007/s12648-026-04125-1","url":null,"abstract":"<div><p>Wave-particle interactions play a fundamental role in the transfer of energy between electromagnetic waves and plasma ions in collisionless space plasmas. This study investigates how electromagnetic ion cyclotron (EMIC) wave-particle interactions modify ion distribution functions in Earth’s magnetosphere using observations from the Magnetospheric Multiscale (MMS) mission. A recent study by Kitamura et al. [41] reported bidirectional energy transfer between EMIC waves and plasma ions. Building upon this work, we examine the response of hydrogen and helium ion velocity distributions during the EMIC wave activity using HPCA and FGM measurements from MMS. Our results show that energetic hydrogen ions exhibit a localized reduction in phase space density within the velocity range of approximately 800-1600 km/s during enhanced EMIC wave activity, consistent with cyclotron resonant interactions. In contrast, the helium ion distributions show a broader enhancement and increased perpendicular anisotropy without a distinct velocity-space depletion, suggesting energization over a wider region of velocity space during the EMIC wave activity. These results provide observational insight into species-dependent EMIC wave-particle interaction processes and energy exchange mechanisms in magnetospheric plasmas, with implications for radiation belt dynamics and geomagnetic activity.</p></div>","PeriodicalId":584,"journal":{"name":"Indian Journal of Physics","volume":"100 11","pages":"4509 - 4520"},"PeriodicalIF":1.7,"publicationDate":"2026-07-22","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"149163135","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}