The European Physical Journal Plus最新文献

{"title":"Investigation of the paramagnetic state and itinerant electron magnetism in YCo12−xFexB6 (x = 0–4) intermetallic compounds","authors":"B. Vallet-Simond,&nbsp;L. V. B. Diop,&nbsp;O. Isnard","doi":"10.1140/epjp/s13360-025-06353-6","DOIUrl":"10.1140/epjp/s13360-025-06353-6","url":null,"abstract":"<div><p>This work aims to investigate the delocalization degree of itinerant electrons in the YCo_{12−<i>x</i>}Fe_<i>x</i>B₆ compounds through Takahashi’s theory of spin fluctuations. The paramagnetic state of the YCo_{12−<i>x</i>}Fe_<i>x</i>B₆ series of compounds is first studied through the evolution of the Curie and Curie–Weiss temperatures as a function of the Fe content. The parent compound YCo₁₂B₆ is a ferromagnet with <i>T</i>_C = 155(3) K, <span>(theta_{C})</span> = 144(3) K and 0.45(4) µ_B/3d at. at 2 K, while the Fe-rich compound YCo₈Fe₄B₆ shows the behaviour of a very weakly ferromagnetic compound with <i>T</i>_C = 51(5) K, <span>(theta_{C})</span> = − 41(5) K and 0.11(4) µ_B/3d at. at 2 K, markers of dominant antiferromagnetic (AFM) interactions. The paramagnetic state was also studied through the evolution of the effective paramagnetic moment compared to the measured moment in the magnetically ordered state. We then applied Takahashi’s theory of spin fluctuations to macroscopic magnetization data to determine the physical parameters <i>T</i>_A and <i>T</i>₀, usually accessible only through local probe methods. The YCo_{12−<i>x</i>}Fe_<i>x</i>B₆ series of compounds was placed on the Deguchi-Takahashi plot, from a slightly delocalized state (p_eff/p_s = 4.27 for x = 0) towards a fully delocalized state (p_eff/p_s = 23.54 for x = 4) by increasing the Fe content. Other markers, like the Curie–Weiss temperature, the metamagnetic transitions for x = 1.5 to 2.5, and the shape parameter <i>s</i> of the thermal evolution of the spontaneous magnetization indicate that this delocalization of the itinerant electron magnetism is accompanied by a progressive strengthening of the AFM interactions as Fe content increases. This study shows that magnetic properties of the YCo_{12<i>−x</i>}Fe_<i>x</i>B₆ family of compounds can only be explained properly by accounting for the spin fluctuations, as they help to transcribe the evolution from a rather localized itinerant electron magnetism towards a completely delocalized case.</p></div>","PeriodicalId":792,"journal":{"name":"The European Physical Journal Plus","volume":"140 5","pages":""},"PeriodicalIF":2.8,"publicationDate":"2025-05-21","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144100255","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"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":"Experimental investigation of buoyancy-driven convective heat transfer of Ag/Fe3O4 hybrid nanofluid inside an enclosure","authors":"Mohammad Kamran,&nbsp;Adnan Qayoum","doi":"10.1140/epjp/s13360-025-06366-1","DOIUrl":"10.1140/epjp/s13360-025-06366-1","url":null,"abstract":"<p>With their superior heat transfer capabilities, hybrid nanofluids are gaining attention as advanced fluids, leveraging the enhanced properties of their individual components. This research investigates the combined effects of Ag and Fe₃O₄ nanoparticles for improving the thermal characteristics of traditional heat transfer fluids like ethylene glycol. Using a two-step methodology, the hybrid nanofluids are prepared and then characterized for their thermal conductivity and viscosity. The thermal conductivity of Ag/Fe₃O₄ shows an increase of up to 9.84% with respect to the base fluid. Similarly, viscosity rises with nanoparticle concentration with the highest viscosity increase of 23% at 0.2% particle loading, while a smaller enhancement of 2.05% occurs at 0.01% concentration. Zeta potential analysis indicated excellent dispersion stability, with values exceeding 30 mV, although stability decreased at higher concentrations due to particle agglomeration. An experimental study on buoyancy-driven convective heat transfer is conducted to evaluate the nanoparticle doping effectiveness. A cubic cavity filled with the hybrid nanofluid is used, and the heat transfer performance is measured by the Nusselt number and heat transfer coefficient. The results show significant improvements in both parameters compared to the base fluid. The Nusselt number increases by up to 7.03%, and the heat transfer coefficient reaches a maximum increase of 12.4% at an optimal nanoparticle concentration of 0.15%. These findings highlight the importance of optimizing nanoparticle concentration for enhanced heat transfer performance in practical applications.</p>","PeriodicalId":792,"journal":{"name":"The European Physical Journal Plus","volume":"140 5","pages":""},"PeriodicalIF":2.8,"publicationDate":"2025-05-21","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144100253","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"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":"Considerations on electromagnetic radiation in Podolsky electrodynamics within a Lorentz-symmetry violating framework","authors":"J. P. Ferreira,&nbsp;Patricio Gaete,&nbsp;José Abdalla Helayël-Neto","doi":"10.1140/epjp/s13360-025-06351-8","DOIUrl":"10.1140/epjp/s13360-025-06351-8","url":null,"abstract":"<div><p>We explore how higher-order derivative terms impact a physical observable within a Lorentz-symmetry violating (LSV) framework. We specifically examine Podolsky electrodynamics coupled with the Carroll-Field-Jackiw model (CFJ). Our analysis shows how vacuum and wave propagation are affected by the interaction of LSV parameters with properties of Podolsky electrodynamics. In this scenario, our results indicate that the new electromagnetic vacuum is birefringent, dichroic, and dispersive. We also point out that the higher-derivative term in the presence of the CFJ space-time anisotropy induces an oscillation mechanism between the photon, which acquires a non-vanishing mass, and the massive vector mode carried by the higher derivative. We then investigate the electromagnetic radiation emitted by a moving charged particle interacting with this new medium. Our analysis reveals that the refractive vacuum through which the charged particle travels influences the electromagnetic radiation, leading to a profile similar to the Cherenkov effect.</p></div>","PeriodicalId":792,"journal":{"name":"The European Physical Journal Plus","volume":"140 5","pages":""},"PeriodicalIF":2.8,"publicationDate":"2025-05-21","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144100254","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"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":"Single-electron capture in proton–helium collision using three-body Coulomb–Born distorted wave (CBDW-3B) approximation","authors":"Sh Azizan,&nbsp;M. Ghaderipour","doi":"10.1140/epjp/s13360-025-06373-2","DOIUrl":"10.1140/epjp/s13360-025-06373-2","url":null,"abstract":"<div><p>In the present context, the three-body Coulomb–Born distorted wave (CBDW-3B) approximation is used to calculate the differential and total cross sections for single-electron capture from helium atoms by proton impact. The primary four-body problem is reduced to the three-body process using the Roothan–Hatree–Fock (RHF) wave function to describe the helium atom as a target. The initial six-dimensional integral of the transition amplitude is reduced to a one-dimensional integral through analytical calculations. The performance of the current three-body method, which neglects dynamic electronic correlation, is evaluated by comparing its results with the four-body methods and corresponding experimental data. Comparisons show reasonable agreement in the total cross sections and the small scattering angles of the differential cross sections.</p></div>","PeriodicalId":792,"journal":{"name":"The European Physical Journal Plus","volume":"140 5","pages":""},"PeriodicalIF":2.8,"publicationDate":"2025-05-21","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144100317","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"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":"Synchrotron-based transmitted, Compton and fluorescence photons from phantom materials","authors":"D. V. Rao,&nbsp;G. E. Gigante,&nbsp;R. Cesareo,&nbsp;A. Brunetti,&nbsp;N. Schiavon,&nbsp;T. Akatsuka,&nbsp;T. Yuasa,&nbsp;T. Takeda","doi":"10.1140/epjp/s13360-025-06152-z","DOIUrl":"10.1140/epjp/s13360-025-06152-z","url":null,"abstract":"<div><p>Synchrotron-based transmitted, Compton and fluorescence photons from phantom materials composed of light elements, for example, Water, PMMA, Polyethylene, Bakelite, Muscle and Bone, are evaluated, using 10, 15, 20, 30 and 40 keV synchrotron X-rays. The SYRMEP beam line facility at Elettra is used as a source of X-rays. The present research is focused to assess the contribution of transmitted, Compton and fluorescence photons, for the above materials with a test phantom of small dimensions with simple approximations. The phantom structures are composed of light elements or mainly tissue substitutes routinely used to simulate radiation interactions in the human body or test objects. To standardize the image parameters, simple mechanical phantoms are designed. The total number of photons in the bounded area, fluorescent photons, interacted Compton photons, Compton photons for a given solid angle and the number of Compton photons detected at 90° are assessed, for the above phantom materials.</p></div>","PeriodicalId":792,"journal":{"name":"The European Physical Journal Plus","volume":"140 5","pages":""},"PeriodicalIF":2.8,"publicationDate":"2025-05-21","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144108524","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"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":"Double Allee effects in a simple tri-trophic system exhibit positive correlation with coexistence and species biodiversity","authors":"Anupam Priyadarshi,&nbsp;Suneel Kumar Bairwa,&nbsp;Prajjwal Gupta,&nbsp;Vinay Kumar","doi":"10.1140/epjp/s13360-025-06379-w","DOIUrl":"10.1140/epjp/s13360-025-06379-w","url":null,"abstract":"<div><p>The Allee effect is a well-known phenomenon that occurs in numerous populations when species densities are low. Many studies have focused on the Allee effect in prey populations, but there is limited research on the mechanism of Allee effects in predators. In multi-trophic systems, predators often experience low population densities due to insufficient food availability, which may lead to Allee effects more frequently in predators than in prey. In this study, a simple tri-trophic model consisting of bottom prey, middle predator and top predator is developed under three different scenarios: when the Allee effect is imposed only on the bottom prey, only on the top predator and simultaneously on both the bottom prey and top predator. The comparative studies are carried out for all the developed models, from which it is observed that the presence of a double Allee effect results in a larger stability domain within the three-species food chain model. This suggests that the double Allee effect has significant control over the coexistence and persistence of the tri-trophic model.</p></div>","PeriodicalId":792,"journal":{"name":"The European Physical Journal Plus","volume":"140 5","pages":""},"PeriodicalIF":2.8,"publicationDate":"2025-05-21","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144108523","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"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":"Resonant soliton interactions of a generalized (2+1)-dimensional soliton equation via asymptotic analysis","authors":"Lihan Zhang,&nbsp;Zhonglong Zhao,&nbsp;Abdul-Majid Wazwaz","doi":"10.1140/epjp/s13360-025-06321-0","DOIUrl":"10.1140/epjp/s13360-025-06321-0","url":null,"abstract":"<div><p>In this paper, we investigate the resonant soliton interactions of a generalized (2+1)-dimensional soliton equation. Via asymptotic analysis, we analyze the amplitudes and phase shifts after the interaction of two-soliton and obtain the expressions of two kinds of temporary intermediate solitons under different conditions. The resonant solutions of two- and three-soliton are discussed, and the exact expressions of new resonant soliton branches are obtained. In particular, by controlling the amplitude of the temporary intermediate soliton generated by the interaction of two-soliton to zero, a new “curved soliton” of the bound state is generated, and by controlling the amplitude of the new resonant branch generated by the interaction of resonant three-soliton to zero, a resonant <i>X</i>-type soliton and a resonant <i>Y</i>-type soliton are obtained, which are works that have not been discussed before. The 2D and 3D images are used to describe these resonant interactions. This study lays a foundation for us to study the resonant interaction between solitons and other nonlinear waves.</p></div>","PeriodicalId":792,"journal":{"name":"The European Physical Journal Plus","volume":"140 5","pages":""},"PeriodicalIF":2.8,"publicationDate":"2025-05-21","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144100314","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"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":"Joint impact of global warming and Allee effect on the phytoplankton–zooplankton dynamics under the mean-reverting Ornstein–Uhlenbeck process","authors":"Tiancai Liao,&nbsp;Honghui Yin","doi":"10.1140/epjp/s13360-025-06340-x","DOIUrl":"10.1140/epjp/s13360-025-06340-x","url":null,"abstract":"<div><p>This work investigates the dynamics of a phytoplankton–zooplankton (PZ) model with global warming and Allee effect, as well as its stochastic version, where stochastic environmental disturbance is characterized by the mean-reverting Ornstein–Uhlenbeck process. In the deterministic PZ model, we numerically and theoretically study the dynamics of stability and Hopf bifurcation. Our results reveal that the weakened global warming can eliminate the bistable phenomenon caused by the Allee effect, while the reduced Allee effect cannot affect the bistable phenomenon caused by global warming. Furthermore, despite that the intensification of global warming cannot change the bistable phenomenon caused by the Allee effect, it can alter the type of bistable. In the stochastic PZ model, we mainly study the existence of stationary distribution, the probability density function, and survival dynamics of plankton, which in turn provides a theoretical basis for numerical simulations. Numerical analysis shows that the intensity of volatility, the speed of reversion, and the variations of global warming and Allee effect can regulate the skewness of stationary distribution for plankton. The numerical results are in good agreement with the theoretical findings.</p></div>","PeriodicalId":792,"journal":{"name":"The European Physical Journal Plus","volume":"140 5","pages":""},"PeriodicalIF":2.8,"publicationDate":"2025-05-21","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144100315","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"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":"Vanadium dioxide-assisted terahertz metasurface for broadband polarization conversion and multi-mode vortex beam generation in full-space","authors":"Yupei Tang,&nbsp;You Li,&nbsp;Xunjun He,&nbsp;Ying Zhang","doi":"10.1140/epjp/s13360-025-06377-y","DOIUrl":"10.1140/epjp/s13360-025-06377-y","url":null,"abstract":"<div><p>In this paper, a terahertz (THz) metasurface for broadband polarization conversion and multi-mode vortex beam generation assisted by vanadium dioxide (VO₂) is proposed. The unit cell is composed of two grating layers parallel to the <i>x</i>-axis and <i>y</i>-axis, respectively, a metal patterned layer, and two dielectric layers. The metal patterned layer consists of a gold cross and a resonant ring with VO₂ filling the opening. In the frequency from 0.26 to 1.32 THz, a cross-polarization conversion rate (PCR) of over 99.9% can be realized, corresponding to a relative bandwidth of 134.2%. By manipulating VO₂ conductivity, dynamic tuning of PCR is obtained. Through precise interlaced phase arrangement by adjusting the angle and width of the metal pattern, three operating modes carrying different functions are formed. While a linear polarization THz wave is incident vertically into the metasurface along the positive and negative directions, respectively, six vortex beam channels with different quantities and topological charges can be achieved. Owing to the orbital angular momentum carried by different vortex beams, the proposed metasurfaces have the potential application prospects in 6G THz communication.</p><h3>Graphical abstract</h3><div><figure><div><div><picture><source><img></source></picture></div></div></figure></div></div>","PeriodicalId":792,"journal":{"name":"The European Physical Journal Plus","volume":"140 5","pages":""},"PeriodicalIF":2.8,"publicationDate":"2025-05-21","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144100316","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"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 complementary integrated approach using non-destructive optical and X-ray methodologies for pigment characterisation on an ancient Egyptian coffin","authors":"Athena Van der Perre,&nbsp;Vanessa Boschloos,&nbsp;Hendrik Hameeuw,&nbsp;Dennis Braekmans","doi":"10.1140/epjp/s13360-025-06360-7","DOIUrl":"10.1140/epjp/s13360-025-06360-7","url":null,"abstract":"<div><p>Museums and culture heritage institutions seek affordable, comparative, non-invasive imaging and analytical techniques to identify and study ancient materials and support their conservation. This study presents a multimodal research approach to assess the art-historical value of an isolated ancient Egyptian polychrome wooden coffin fragment from the KU Leuven archaeological collections, dating to the Third Intermediate Period (ca. 945–656 BCE). In a first step imaging techniques (standard even and raking photography, visible-induced luminescence, visible imaging spectrometry, white light and multispectral multilight reflectance imaging, narrow band multispectral imaging) were applied on the coffin’s surface to document its state, to identify and differentiate original and restored areas, and to select spots for more in-depth spectroscopic molecular and elemental analysis (fibre optics reflectance spectroscopy, X-ray fluorescence spectroscopy). These allowed pigment identification, characterisation of mixtures and provided a deeper understanding of the object’s condition and used painting techniques. All applied methodologies can be used in situ. The resulting datasets are curated into a multilayered IIIF Mirador 3 viewer, presenting all results in a complete and user-friendly environment.</p><h3>Graphical abstract</h3>\u0000<div><figure><div><div><picture><source><img></source></picture></div></div></figure></div></div>","PeriodicalId":792,"journal":{"name":"The European Physical Journal Plus","volume":"140 5","pages":""},"PeriodicalIF":2.8,"publicationDate":"2025-05-21","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://link.springer.com/content/pdf/10.1140/epjp/s13360-025-06360-7.pdf","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144108522","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"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}