Indian Journal of Physics最新文献

{"title":"Effects of V and Tc co-doping on the electronic and magnetic properties of TiO2","authors":"A. Maftouh,&nbsp;R. Redouane,&nbsp;L. B. Drissi,&nbsp;O. El Fatni,&nbsp;R. Ahl Laamara,&nbsp;I. Serifi,&nbsp;Y. Ezaier,&nbsp;Y. Lghazi,&nbsp;A. Hader","doi":"10.1007/s12648-026-04064-x","DOIUrl":"10.1007/s12648-026-04064-x","url":null,"abstract":"<div><p>First-principles calculations based on density functional theory (DFT) were performed using the Korringa–Kohn–Rostoker method combined with the coherent potential approximation (KKR-CPA) to investigate the electronic, magnetic, and thermal stability of Ti_1−xTc_xO₂, TiO_2−xV_x, and Ti_1−xTc_xO_2−yV_y diluted magnetic semiconductor systems for various dopant concentrations. The KKR-CPA approach is particularly suitable for describing substitutional disorder in doped materials, allowing for an accurate treatment of random doping without the need for large supercell models. The results reveal that both Tc- and V-doped rutile TiO₂ exhibit half-metallic behavior with spin polarization at the Fermi level. Furthermore, the disordered local moment (DLM) state is found to be energetically more stable than the ferromagnetic (FM) state in Tc-doped TiO₂, whereas V-doped TiO₂ stabilizes in a ferromagnetic configuration. Co-doping with V introduces hole carriers that promote the stabilization of ferromagnetism in Tc-doped systems. The calculated Curie temperatures (T_C) exceed room temperature (RT), indicating that these materials are promising candidates for spintronic applications.</p></div>","PeriodicalId":584,"journal":{"name":"Indian Journal of Physics","volume":"100 9","pages":"3741 - 3752"},"PeriodicalIF":1.7,"publicationDate":"2026-07-14","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"148752048","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":"Electromagnetic response and coulomb form factors of (^{20})Ne from large-space configuration mixing","authors":"Berun N. Ghafoor,&nbsp;Awara R. Mohammed,&nbsp;Aziz H. Fatah","doi":"10.1007/s12648-026-04120-6","DOIUrl":"10.1007/s12648-026-04120-6","url":null,"abstract":"<div><p>In this work, the structure of <span>(^{20})</span>Ne nucleus is investigated. We calculated excitation energies, charge and matter density distributions, root mean square radii, reduced transition probabilities, magnetic dipole moments, electric quadrupole moments, and elastic and inelastic longitudinal form factors for the ground and some low-lying positive-parity excited states. The calculations were carried out using the extended model spaces: spsdpf (no-core) with WBT interaction, psd (<span>(^{4})</span>He core) with PSDMWK interaction, zbm (<span>(^{12})</span>C core) with ZBMI interaction, and sd (<span>(^{16})</span>O core) with USDA interaction. For each calculation, the Harmonic Oscillator (HO), Woods–Saxon (WS), and Skyrme potentials with parameterizations SkXcsb, SLy4, SkXta, and SkXtb were employed. The Skyrme–Hartree–Fock (SHF) approach and shell model were used as the theoretical framework, and the core-polarization effect was treated using the Tassie model. The results were compared with the available experimental data, and good agreement was achieved.</p></div>","PeriodicalId":584,"journal":{"name":"Indian Journal of Physics","volume":"100 11","pages":"4907 - 4924"},"PeriodicalIF":1.7,"publicationDate":"2026-07-14","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"149163059","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":"Phase plane dynamics of seismic wave subjected to nonlinear stresses at upper gap condition","authors":"Guy Merlin Nkeumaleu,&nbsp;Kagho Ymele Laurent,&nbsp;Desire Ndjanfang","doi":"10.1007/s12648-026-04138-w","DOIUrl":"10.1007/s12648-026-04138-w","url":null,"abstract":"<div><p>This study highlights the impact of stress nonlinearity on seismic-wave dynamics. When deformations are no longer elastic, linear elasticity is no longer valid, and the medium response becomes nonlinear. In this work, we use the Hardin–Drnevich law for nonlinear shear stresses and a nonlinear Hooke-type law for compression. By incorporating these constitutive laws, we derive a displacement-field equation analogous to a nonlinear Klein–Gordon model with anharmonic, cubic, and quartic interactions embedded in a substrate potential. The resulting amplitude equation contains singular-curve terms that provide additional insight into seismic-wave behavior. Wave amplitudes are obtained using a bifurcation approach based on phase portraits. Under different parameter regimes, distinct classes of solutions are found, and the corresponding constants related to nonlinear coefficients are extracted. We further show how singular curves affect stress evolution in the propagation medium.</p></div>","PeriodicalId":584,"journal":{"name":"Indian Journal of Physics","volume":"100 11","pages":"4893 - 4905"},"PeriodicalIF":1.7,"publicationDate":"2026-07-13","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"149163156","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":"A Caputo-Fabrizio fractional optimal control framework, analysis and simulation for the dynamics of tomato yellow leaf curl disease","authors":"Ritu Agarwal,&nbsp;Chhaya Midha","doi":"10.1007/s12648-026-04108-2","DOIUrl":"10.1007/s12648-026-04108-2","url":null,"abstract":"<div><p>Tomatoes rank as the second most important vegetable crop globally, making their health and productivity a critical concern. Tomato Yellow Leaf Curl (TYLC) disease poses a significant threat, necessitating focused research due to its widespread impact on this highly consumed vegetable. This study presents an empirical analysis to better understand and address the disease’s effects. It explores a system of fractional differential equations, employing the Caputo-Fabrizio (C-F) fractional operator, to model the interaction between tomato plants and viruses within a crop field. The model focuses on exploring optimal control strategies aimed at mitigating the spread of the Tomato Yellow Leaf Curl (TYLC) disease. The optimal control problem is rigorously analyzed using Pontryagin’s Maximum Principle (PMP), leading to the derivation of an optimality system. The resulting system is numerically simulated through a forward-backward sweep algorithm. These simulations effectively demonstrate the impact of various control intervention combinations on the disease’s transmission dynamics.</p></div>","PeriodicalId":584,"journal":{"name":"Indian Journal of Physics","volume":"100 11","pages":"4823 - 4846"},"PeriodicalIF":1.7,"publicationDate":"2026-07-12","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"149163129","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 insights into LiZrPtZ (Z = Al, Ga) quaternary Heusler semiconductors for high-temperature thermoelectric applications","authors":"Khadidja Sassoui","doi":"10.1007/s12648-026-04131-3","DOIUrl":"10.1007/s12648-026-04131-3","url":null,"abstract":"<div><p>This study explores the properties of newly identified Li-based quaternary Heusler compounds LiZrPtZ (Z = Al, Ga) to assess their suitability for high-temperature thermoelectric applications. Using density functional theory (DFT) in combination with Boltzmann transport equations, we systematically examined their structural, electronic, elastic, thermodynamic, and thermoelectric properties. The results confirm the stability of the face-centred cubic structures, with both compounds exhibiting indirect semiconducting band gaps of 1.743 and 1.748 eV for LiZrPtAl and LiZrPtGa, respectively, as obtained using the HSE06 hybrid functional. Elastic and mechanical analyses demonstrate that these alloys are mechanically stable and ductile. Thermodynamic calculations indicate high Debye temperatures of 390.02 K for LiZrPtAl and 348.58 K for LiZrPtGa, and melting temperatures of 1707.62 and 1581.60 K, respectively. Thermoelectric evaluations reveal promising figures of merit (ZT) of 0.59 and 0.52 for LiZrPtGa and LiZrPtAl, respectively, at 1500 K. Collectively, these findings suggest that LiZrPtZ (Z = Al, Ga) compounds are promising candidates for sustainable energy harvesting and advanced thermoelectric technologies.</p></div>","PeriodicalId":584,"journal":{"name":"Indian Journal of Physics","volume":"100 11","pages":"4799 - 4812"},"PeriodicalIF":1.7,"publicationDate":"2026-07-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"149163154","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":"Stability and statistical validation of the Sáez-Ballester theory in multidimensional spacetime","authors":"Navya Jain,&nbsp;R. K. Mishra","doi":"10.1007/s12648-026-04110-8","DOIUrl":"10.1007/s12648-026-04110-8","url":null,"abstract":"<div><p>This paper explores the impact of extra spatial dimensions on scalar field dynamics and cosmic evolution within the framework of the Sáez–Ballester scalar-tensor theory. Using higher-dimensional FLRW metric, a time-dependent deceleration parameter linked to the Hubble parameter <span>(H)</span> is introduced to describe the universe’s smooth transition from deceleration to acceleration. The inclusion of extra dimensions through a conformal transformation simplifies the field equations and clarifies the behavior of key cosmological quantities such as energy density, pressure, and the scalar field. The model’s stability is examined via perturbation analysis, where small fluctuations in the energy density are studied and their temporal evolution is numerically analyzed using the fourth-order Runge–Kutta method. The EoS parameter <span>(xi (z))</span> approaches <span>(-1)</span>, indicating a shift toward a dark energy dominated era, while all energy conditions vanish as <span>(z rightarrow -1)</span>. Model parameters are further constrained using Hubble, Pantheon+SH0ES, and DESI DR2 BAO datasets through Maximum Likelihood Estimation and Markov Chain Monte Carlo techniques, confirming the stability and observational consistency of the proposed higher-dimensional model.</p></div>","PeriodicalId":584,"journal":{"name":"Indian Journal of Physics","volume":"100 10","pages":"4021 - 4041"},"PeriodicalIF":1.7,"publicationDate":"2026-07-10","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"148909716","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":"An analytical study of the effects of magnetic field gradient and density gradient on the growth rate of Weibel electromagnetic instability with a fast ignition approach in magneto-inertial fusion","authors":"Seyed Mohammad Eftekhari,&nbsp;Mohammad Mahdavi","doi":"10.1007/s12648-026-04128-y","DOIUrl":"10.1007/s12648-026-04128-y","url":null,"abstract":"<div><p>Magneto-Inertial Fusion (MIF) integrates magnetic confinement, pinch mechanisms, and hybrid methodologies, necessitating the use of a liner to compress and thermally excite a magnetized plasma target. In recent years, this approach has garnered significant attention owing to the application of a magnetic field and the considerable reduction in the laser energy required for fuel compression. In this method, the reduction in electron thermal conductivity leads to an increase in the hot spot temperature, reducing the compression rate compared to inertial confinement fusion (ICF). In this study, the growth rate of the Weibel electromagnetic instability is investigated analytically in a magnetized plasma region under the presence of an external magnetic field, considering the density gradient and magnetic field gradient simultaneously. The obtained results indicate that the presence and increase of an external magnetic field lead to a reduction in the growth rate of Weibel instability. The obtained results indicate that the presence of an external magnetic field, as well as its increase, lead to a reduction in the growth rate of Weibel instability. Also, an increase in the magnetic field gradient and the density gradient leads to a decrease in the growth rate of Weibel instability, while an increase in temperature anisotropy leads to an increase in instability growth. A comparative analysis of the effects exerted by density and magnetic field gradients on the Weibel instability growth rate indicates that minor fluctuations in the magnetic field gradient exert a more substantial influence than those of the density gradient. It has also been shown that doubling the magnetic field gradient at a constant density gradient reduces the maximum growth rate of the Weibel instability by approximately 30%. Consequently, by optimizing the magnetic field and density gradients, as well as modulating the growth rate of the Weibel instability, one may establish the necessary conditions for the deposition of relativistic electron beam energy, thereby facilitating effective ignition within the fuel center.</p></div>","PeriodicalId":584,"journal":{"name":"Indian Journal of Physics","volume":"100 10","pages":"4439 - 4446"},"PeriodicalIF":1.7,"publicationDate":"2026-07-09","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"148909523","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":"Ionization and charge exchange cross-sections in Be3+ + H collision: classical and quasi-classical trajectory monte carlo approaches","authors":"Saed J. Al Atawneh","doi":"10.1007/s12648-026-04117-1","DOIUrl":"10.1007/s12648-026-04117-1","url":null,"abstract":"<div><p>This study presents cross-section calculations for ionization, electron capture, and system breakdown in collisions of beryllium ions (Be³⁺) with hydrogen atoms. While electron capture in this system has been previously investigated by Shimakura (1988) and Liu &amp; Wang (2013) using quantum molecular-orbital methods, the present work provides the first simultaneous calculation of all three processes (ionization, capture, and breakdown) within a unified four-body model using both Classical Trajectory Monte Carlo (CTMC) and Quasi-Classical Trajectory Monte Carlo (QCTMC) methods. Simulations cover an impact energy range of 0.1–11 keV amu^-1 pertinent to fusion and astrophysical plasmas. Comparisons with previous theoretical and experimental data for analogous systems, specifically Li³⁺+ H and B³⁺ + H collisions, demonstrate good agreement at higher energies (above 2 keV amu^-1). At lower energies, both the CTMC and QCTMC methods exhibit a marginal overestimation of the cross-section compared with earlier studies. Notably, the QCTMC model yields systematically higher cross-sections than the CTMC, especially at low energies, reflecting the impact of quantum corrections such as the Heisenberg correction term. This work provides previously unavailable multi-channel cross-section data for the Be³⁺+ H system and validates the QCTMC approach as a robust tool for modeling ion–atom collisions where experimental data remain limited.</p></div>","PeriodicalId":584,"journal":{"name":"Indian Journal of Physics","volume":"100 11","pages":"4521 - 4531"},"PeriodicalIF":1.7,"publicationDate":"2026-07-09","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"149163093","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":"An in-depth analysis of interplanetary drivers and their causal mechanisms for severe geomagnetic storms during the period from 1996 to 2006","authors":"Swapnil Garg,&nbsp;Omkar Prasad Tripathi,&nbsp;Saket Kumar,&nbsp;Palak Singh Thakur","doi":"10.1007/s12648-026-04121-5","DOIUrl":"10.1007/s12648-026-04121-5","url":null,"abstract":"<div><p>This study investigated the interplanetary drivers of 26 severe geomagnetic storms that occurred during Solar Cycle 23, spanning 1996 to 2006. The analysis focused on severe events with a peak Disturbance Storm Time (Dst) index value ≤ −150 nT. Using data from the OMNI database, the study examines the relationships between storm intensity and various interplanetary and geomagnetic parameters. The results confirm that all 26 events were initiated by a prolonged southward component of the interplanetary magnetic field (IMF-B_z), as measured by the GSM coordinate system, a condition crucial for facilitating magnetic reconnection and the subsequent transfer of energy to the Earth’s magnetosphere. While Dst is used to monitor the equatorial ring current intensity, Kp and ap are analyzed as indices reflecting global activity, noting that Kp is notably sensitive to solar wind dynamic pressure. Strong correlation coefficients are found between the peak Dst and the peak values of the total interplanetary magnetic field (IMF − B) (0.65) and its southward component (IMF − Bz) (0.67). The correlation with IMF-B is expected as high-field regions increase the probability of extreme −B_z; however, we quantify this relationship to provide a baseline for comparison against solar proxies. It is emphasized that the fundamental physical driver is the convective electric field (E_y = V × B_z), which facilitates energy transfer. The highest correlations are observed with the geomagnetic indices Ap (0.70) and Kp (0.70). In contrast, solar proxies such as the sunspot number (SSN) and solar radio flux (F10.7) showed only weak correlations (0.26 and 0.32, respectively). A moderate correlation is observed between peak Dst and Solar wind velocity (V_sw) (CC = 0.44). Analysis of the interplanetary structures revealed that simple magnetic clouds (sMC), sheath fields (SH), and combined sheath and magnetic cloud structures (SH + MC) collectively accounted for over 75% of these severe storms. The distribution of these drivers was highly dependent on the phase of the solar cycle, with sheath fields dominating at solar maximum and magnetic clouds prevailing during the rising and declining phases. This research shows that severe geomagnetic storm intensity is critically determined by specific interplanetary conditions (B, B_z, and V_sw), which have a much stronger influence than general solar activity proxies, SSN F (10.7), thus improving space weather forecasting accuracy.</p></div>","PeriodicalId":584,"journal":{"name":"Indian Journal of Physics","volume":"100 11","pages":"4489 - 4508"},"PeriodicalIF":1.7,"publicationDate":"2026-07-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"149163130","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 K-doped Rb7KSn4H16 for hydrogen storage: a study of structural, electronic, mechanical, optical, dynamic, and thermal properties","authors":"Cihan Kürkçü,&nbsp;Cengiz Soykan","doi":"10.1007/s12648-026-04107-3","DOIUrl":"10.1007/s12648-026-04107-3","url":null,"abstract":"<div><p>The development of efficient and environmentally friendly solid-state hydrogen storage materials remains a major challenge for clean energy technologies. In this study, the structural, electronic, mechanical, optical, vibrational, thermal, and hydrogen storage properties of K-doped Rb₇KSn₄H₁₆ were systematically investigated using first-principles density functional theory calculations. The compound was constructed by partial substitution of Rb with K in the parent Rb₂SnH₄ structure to evaluate the effect of alkali-metal doping on hydrogen storage performance and physical properties. The calculated negative formation energy confirms thermodynamic stability, while the absence of imaginary phonon frequencies demonstrates dynamical stability. Electronic structure calculations reveal that Rb₇KSn₄H₁₆ is a direct band gap semiconductor with a band gap of 0.722 eV. Mechanical analysis indicates brittle behavior with dominant covalent bonding characteristics. Optical results show enhanced low-energy reflectivity and optical conductivity after K substitution. Thermal calculations indicate robust lattice stability with heat capacity saturation near 140 cal/mol K at elevated temperatures. The compound exhibits a gravimetric hydrogen storage capacity of approximately 2.88 wt%, demonstrating the potential of alkali-metal substitution for tuning complex hydrides. Although this value remains below the current U.S. DOE target for practical applications, the combined thermodynamic, mechanical, and dynamical stability highlights Rb₇KSn₄H₁₆ as a promising candidate for future solid-state hydrogen storage research.</p></div>","PeriodicalId":584,"journal":{"name":"Indian Journal of Physics","volume":"100 11","pages":"4657 - 4667"},"PeriodicalIF":1.7,"publicationDate":"2026-07-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://link.springer.com/content/pdf/10.1007/s12648-026-04107-3.pdf","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"149163104","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}