物理最新文献

{"title":"Cryogenic magnetic properties and magnetocaloric performance in the RE(Fe0.25Co0.75)2H3 (RE = Ho and Er) laves phase compounds","authors":"I. Chaaba,&nbsp;R. M’nassri","doi":"10.1007/s00339-025-08294-4","DOIUrl":"10.1007/s00339-025-08294-4","url":null,"abstract":"<div><p>Exploiting the magnetocaloric effect for low-temperature magnetic refrigeration presents a compelling green technology for cryogenic applications in space science and hydrogen liquefaction. In this work, we investigate the structural and magnetic properties of RE(Fe_0.25Co_0.75)₂H₃ compounds, where RE represents Ho and Er. These compounds crystallize in the cubic MgCu₂ (C15) structure with a lattice parameter of 7.62 Å for RE = Ho and 7.60 Å for RE = Er. Magnetization measurements as a function of temperature, performed in a 0.05 T magnetic field, reveal that both hydrides exhibit ferrimagnetic behaviour. The Curie temperatures (T_C) for Ho and Er hydrides were determined to be 124 K and 75 K, respectively. We studied the magnetic entropy change (−∆S_M) and refrigerant capacity (RC) of both samples by measuring isothermal magnetizations under various field changes between 0 and 7 Tesla. With increasing applied field, both −∆S_M and RC increase, and the temperature span of the −∆S_M versus T plots widens. Furthermore, from the −∆S_M (T) curves under an external magnetic field change of 5 T, we observed a maximum -ΔS_M of ∼ 3.11 and 4.41 Jkg^-1K^-1 for RE = Ho and Er, respectively. The corresponding temperature-averaged entropy change over a 10 K temperature span was TEC_10K ∼2.9 and ∼3.8 Jkg^-1K^-1 for RE = Ho and Er, respectively. These results indicate that Er(Fe_0.25Co_0.75)₂H₃ exhibits superior thermomagnetic properties compared to Ho(Fe_0.25Co_0.75)₂H₃ particularly for low-temperature magnetic cooling applications.</p></div>","PeriodicalId":473,"journal":{"name":"Applied Physics A","volume":"131 3","pages":""},"PeriodicalIF":2.5,"publicationDate":"2025-02-04","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143108028","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"材料科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Enhanced multifunctionality of SnO2 and W-doped SnO2 thin films synthesized via ultrasonic spray pyrolysis: applications in UV photodetectors, photocatalysis, and tunable surface hydrophilicity","authors":"Sabrina Roguai,&nbsp;Abdelkader Djelloul","doi":"10.1007/s00339-025-08256-w","DOIUrl":"10.1007/s00339-025-08256-w","url":null,"abstract":"<div><p>SnO₂, Sn_1-xW_xO [2, 5, 10 at.%] thin films were synthesised using the ultrasonic spray pyrolysis. Structural analysis revealed that W doping significantly improved crystallinity and modified the morphology of SnO₂ thin films, with 5% W doping resulting in the most uniform grain growth and optimal structural properties. In contrast, excessive doping at 10% induced lattice distortions and particle agglomeration. Fourier transform infrared spectroscopy (FTIR) analysis highlighted intensified O–H and H–O–H vibrational modes with increasing W content, indicating enhanced surface hydroxylation, which is crucial for optical and catalytic applications. The optical bandgap widened from 3.63 eV for pristine SnO₂ to 3.84 eV for 2% W-SnO₂ and stabilized around 3.82–3.83 eV for 5% and 10% W-SnO₂. Thermoelectric studies revealed improved electrical conductivity at 5% W doping due to an increased carrier concentration of 2.49 × 10¹⁸ cm⁻³. Notably, the Seebeck coefficient (│S│) showed partial recovery at 10% doping, suggesting a nuanced balance between carrier density and scattering mechanisms. For photodetection, the 5%-W-doped SnO₂ demonstrated a markedly enhanced Ultraviolet response, with significantly higher peak currents during UV exposure. Photocatalytic experiments showed superior performance for the 5% W-SnO₂ film, achieving 98% methylene blue degradation under Ultraviolet light within 150 min. Furthermore, contact angle measurements revealed a transition from hydrophilicity to hydrophobicity. The water contact angle increased from hydrophilic behaviour in pure SnO₂ to highly hydrophobic surfaces at 10% W doping. This change underscores the tunable surface properties of W-doped SnO₂ thin films. These findings establish them as promising candidates for multifunctional applications in optoelectronics, photocatalysis, and surface engineering.</p></div>","PeriodicalId":473,"journal":{"name":"Applied Physics A","volume":"131 3","pages":""},"PeriodicalIF":2.5,"publicationDate":"2025-02-04","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143108024","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"材料科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Exploring the evolution of structure growth in the universe with field-fluid interactions through dynamical stability analysis","authors":"Anirban Chatterjee,&nbsp;Abhijit Bandyopadhyay,&nbsp;Debasish Majumdar","doi":"10.1140/epjc/s10052-025-13856-0","DOIUrl":"10.1140/epjc/s10052-025-13856-0","url":null,"abstract":"<div><p>We investigate an interacting quintessence dark energy – dark matter scenario and its impact on structure formation by analyzing the evolution of scalar perturbations. The interaction is introduced by incorporating a non-zero source term into the continuity equations of the two sectors (with opposite signs), modeled as <span>(bar{Q}_0 equiv alpha bar{rho }_textrm{m}(H + kappa dot{phi }))</span>. The coupling parameter <span>(alpha )</span> and the parameter <span>(lambda )</span> involved in quintessence potential <span>(V(phi ) = V_0e^{-lambda kappa phi })</span>, play crucial roles in governing the dynamics of evolution examined within the present framework. The cosmic evolution, within this context, is depicted as a first-order autonomous system of equations involving appropriately chosen dynamical variables. We analyzed the associated stability characteristics and growth rate of perturbations, and obtained domains in the (<span>(alpha -lambda )</span>) parameter space for which fixed points can exhibit stable and non-phantom accelerating solutions. Depending on its magnitude, the coupling parameter <span>(alpha )</span> has the potential to change the characteristics of certain critical points, altering them from attractors to repellers. This model effectively captures the evolutionary features of the universe across its various phases at both the background and perturbation levels. The issue of cosmic coincidence can also be addressed within the framework of this model. We also observed that for a moderate strength of coupling, the growth rate of matter perturbation extends into the distant future.</p></div>","PeriodicalId":788,"journal":{"name":"The European Physical Journal C","volume":"85 2","pages":""},"PeriodicalIF":4.2,"publicationDate":"2025-02-04","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://link.springer.com/content/pdf/10.1140/epjc/s10052-025-13856-0.pdf","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143108175","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"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":"Flexibly tunable dual-mode semiconductor laser based on amplified feedback","authors":"Huibin Chen,&nbsp;Zhenyu You,&nbsp;Kaize Xu","doi":"10.1007/s00340-024-08378-8","DOIUrl":"10.1007/s00340-024-08378-8","url":null,"abstract":"<div><p>We propose and fabricate a monolithically integrated dual-mode semiconductor laser (DML) based on optical amplified feedback, where the adjustable optical self-injection feedback could induce dual-wavelength lasing, and the sub-millimeter total cavity length provides access to be microwave source. When keeping the injection current of semiconductor optical amplifier (SOA) be constant, inject different current for the segment of distributed feedback laser (DFB), we have achieved tunable microwave signal with different ranges of 10 GHz and 18 GHz respectively, which significantly simplifies the system configuration and reduces the footprint, power consumption and cost. Besides, through a special current injection scheme for the two-segment semiconductor laser, whole wavelength tuning with fixed wavelength spacing can also be realized. It provides a convenient and low-cost photonic solution for flexible and tunable microwave sources.</p></div>","PeriodicalId":474,"journal":{"name":"Applied Physics B","volume":"131 3","pages":""},"PeriodicalIF":2.0,"publicationDate":"2025-02-04","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143107928","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":"Weak gravity conjecture validation with photon spheres of quantum corrected Reissner–Nordstrom–AdS black holes in Kiselev spacetime","authors":"Mohammad Reza Alipour,&nbsp;Mohammad Ali S. Afshar,&nbsp;Saeed Noori Gashti,&nbsp;Jafar Sadeghi","doi":"10.1140/epjc/s10052-025-13857-z","DOIUrl":"10.1140/epjc/s10052-025-13857-z","url":null,"abstract":"<div><p>In this study, we investigate the Weak Gravity Conjecture (WGC) in the context of quantum-corrected Reissner–Nordstrom–AdS (RN-AdS) black holes within Kiselev spacetime. Our focus is on photon spheres, which serve as markers for stable and unstable photon spheres. We confirm the validity of the WGC by demonstrating that quantum corrections do not alter the essential charge-to-mass ratio, thereby supporting the conjecture’s universality. Our analysis reveals that black holes with a charge greater than their mass <span>((Q &gt; M))</span> possess photon spheres or exhibit a total topological charge of the photon sphere <span>((text {PS} = -1),)</span> which upholds the WGC. This finding is significant as it reinforces the conjecture’s applicability even in the presence of quantum corrections. Furthermore, we examine various parameter configurations to understand their impact on the WGC. Specifically, we find that configurations with <span>(omega = -frac{1}{3})</span> and <span>(omega = -1)</span> maintain the conjecture, indicating that these values do not disrupt the charge-to-mass ratio required by the WGC. However, for <span>(omega = -frac{4}{3},)</span> the conjecture does not hold, suggesting that this particular parameter value leads to deviations from the expected behavior. These results open new directions for research in quantum gravity, as they highlight the importance of specific parameter values in maintaining the WGC. The findings suggest that while the WGC is robust under certain conditions, there are scenarios where it may be challenged, prompting further investigation into the underlying principles of quantum gravity.</p></div>","PeriodicalId":788,"journal":{"name":"The European Physical Journal C","volume":"85 2","pages":""},"PeriodicalIF":4.2,"publicationDate":"2025-02-04","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://link.springer.com/content/pdf/10.1140/epjc/s10052-025-13857-z.pdf","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143107806","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"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":"Highly sensitive PCF-SPR sensor for simultaneous and independent sensing of refractive index and temperature","authors":"Huipeng Chen,&nbsp;Zhenshi Chen,&nbsp;Xiaochun Xu,&nbsp;Huilong Liu,&nbsp;Lei Wan","doi":"10.1007/s00340-025-08384-4","DOIUrl":"10.1007/s00340-025-08384-4","url":null,"abstract":"<div><p>Refractive index (RI) is an important index to determine the composition of a substance, however, it is affected by temperature changes. Therefore, it is of great significance to design a sensor in which temperature variation will not affect the measurement of RI. In this paper, a double D-shaped photonic crystal fiber based on surface plasmon resonance (PCF-SPR) sensor is proposed to realize simultaneous and independent sensing of RI and temperature. The results show that the maximum sensitivity of the proposed sensor reaches 32,100 nm/RIU and 5.9 nm/℃ for RI and temperature, respectively. In addition, the changes of the air hole radius and the polishing depth will not cause the drift of the resonant wavelength. This advantage is conducive to fabricate a PCF-SPR sensor with high fault tolerance rate and lower production costs in practical process. The paper provides a reference for developing a high-sensitivity and multi-parameter measurement sensor used in water pollution monitoring and bio-sensing.</p></div>","PeriodicalId":474,"journal":{"name":"Applied Physics B","volume":"131 3","pages":""},"PeriodicalIF":2.0,"publicationDate":"2025-02-04","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143107937","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":"Analysis for 3D thermal conducting micropolar nanofluid via artificial neural network","authors":"Mamoon Aamir,&nbsp;Sultan Alshehery,&nbsp;Aqsa Zafar Abbasi,&nbsp;Muhammad Umer Sohail,&nbsp;Naveed Khan,&nbsp;Abdelhakim Mesloub,&nbsp;Mariyam Sattar,&nbsp;Lioua Kolsi","doi":"10.1140/epjp/s13360-025-06022-8","DOIUrl":"10.1140/epjp/s13360-025-06022-8","url":null,"abstract":"<div><p>This paper considers the Darcy–Forchheimer flow over a micropolar nanofluid by using an intelligent backpropagated neural network with Levenberg–Marquardt scheme. The PDEs governing the DFF-MNFM are reduced into ODEs through some appropriate transformations. A reference dataset is prepared from HAM by changing several key parameters, such as the porosity parameter (<i>γ</i>), Reynolds number (Re), coupling parameter (<i>N</i>₁), rotation parameter (Kr), coefficient of inertia (Fr), viscosity gradient parameter (<i>N</i>₂), and Brownian motion parameter (Nb), for all proposed IBNN-LMS scenarios. The estimated solutions of the IBNN-LMS are analyzed and compared with reference results. The results suggest that for high values of the Reynolds number, Re, the fluid velocity is increased at the surface, and with Kr, increasing velocity on the surface of the fluid increases but decreases beyond the surface. A rise in the value of <i>γ</i> enhances velocity closer to the surface while diminishing the velocity beyond the surface distance. The rise of <i>N</i>₁ enhances the speed of the microrotation of fluid closer to the surface. In addition, the higher temperature and concentration profiles enhance the value of Nb. For the validation of IBNN-LMS approach, its efficiency is justified through convergence analysis of MSE, regression indices, and error spectrum evaluations that represent its robustness in solving complicated fluid flow problems.</p></div>","PeriodicalId":792,"journal":{"name":"The European Physical Journal Plus","volume":"140 2","pages":""},"PeriodicalIF":2.8,"publicationDate":"2025-02-04","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143108178","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":"Real-time monitoring method for gadolinium concentration in a water Cherenkov detector","authors":"Yoshihiro Iwata,&nbsp;Hiroyuki Sekiya,&nbsp;Chikara Ito","doi":"10.1007/s00339-025-08283-7","DOIUrl":"10.1007/s00339-025-08283-7","url":null,"abstract":"<div><p>Time-resolved laser-induced luminescence spectroscopy is useful for real-time measurement of lanthanide ion concentrations in aqueous solution. Gadolinium ions (Gd<span>(^{3+})</span>), in particular, have a long (<span>(sim)</span>ms) emission lifetime, so that the ion emission can be easily distinguished from scattering of the excitation pulsed laser without the need for a monochromator. In this work, we have developed a real-time monitoring method for Gd concentration in water, aiming at application to the Super-Kamiokande (SK) water Cherenkov detector in which 0.03% Gd is currently dissolved in the form of sulfate for the observation of supernova relic neutrino events. The basic concept is to install a tube to run a portion of the water sample through a quartz cell (2 cm on each side), where a ns-pulsed laser at 266 nm is irradiated to excite Gd<span>(^{3+})</span> ions. The generated Gd<span>(^{3+})</span> ion emission at 312 nm is collimated by a lens, transmitted through a bandpass filter, and then detected by a photomultiplier tube placed about 10 cm away from the quartz cell. While lower Gd concentration and higher pulsed laser energy resulted in shorter Gd<span>(^{3+})</span> emission lifetime, good linearity was confirmed between Gd concentration and normalized peak emission voltage in the wide range of 1–1000 ppm (0.1%) Gd in ultrapure water. The detection limit, defined as three times the standard deviation of the background level, was determined to be <span>(sim)</span>60 ppb for Gd sulfate in ultrapure water. This value is about two orders of magnitude better than the reported value using laser-induced breakdown spectroscopy, and is close to that using inductively coupled plasma optical emission spectrometry which requires sample introduction into the spectrometer. Sulfate ions in aqueous solution appear to have a smaller quenching effect than O–H vibrations of water molecules coordinated to the cation. By confirming a detection sensitivity below the ppm-level, this method could be effective for monitoring of drainage water from the SK detector tank as well. Our real-time monitoring method is expected to support the long-term operation of the SK-Gd project.</p></div>","PeriodicalId":473,"journal":{"name":"Applied Physics A","volume":"131 3","pages":""},"PeriodicalIF":2.5,"publicationDate":"2025-02-04","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143107832","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"材料科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"A self-powered wearable sensor for infant fall detection based on triboelectric nanogenerator","authors":"Luoke Hu,&nbsp;Hui Meng,&nbsp;Zhonggui Xu,&nbsp;Yong Wang","doi":"10.1007/s00339-025-08305-4","DOIUrl":"10.1007/s00339-025-08305-4","url":null,"abstract":"<div><p>Infant fall detection is critical for the timely identification of fall events, assessment of the severity, and reduction of potential injuries. Traditional fall detection technologies typically rely on devices such as cameras, force sensors, accelerometers, and gyroscopes. While these devices provide accurate measurements, they are often expensive, require complex installation, and depend on external power sources, leading to higher system complexity and maintenance costs. This paper reports a self-powered, wearable sensor based on triboelectric nanogenerator (TENG) for infant fall detection, featuring a bridge-structured PDMS layer and a copper foil electrode. By attaching the TENG sensor to the skin or joints of an infant model or human body, we successfully detected fall status, frequency, impact intensity, and impact localization. The sensor achieves a minimum detectable acceleration of 0.4 g on human skin, with a sensitivity of 2.6 V/g. When integrated with artificial intelligence algorithms, the system achieves over 94% accuracy in predicting fall locations. Furthermore, the sensor maintains a stable output after tens of thousands of cycles, demonstrating exceptional stability and repeatability. Compared to traditional fall detection technologies, the proposed system offers several advantages, including low cost, simple manufacturing, easy installation, self-powered operation, and high portability.</p></div>","PeriodicalId":473,"journal":{"name":"Applied Physics A","volume":"131 3","pages":""},"PeriodicalIF":2.5,"publicationDate":"2025-02-04","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143107834","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"材料科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Enhanced THz emission from photoconductive antennas by integrating photonic structures on a semi-insulating GaAs substrate","authors":"Goutam Rana,&nbsp;Abhishek Gupta,&nbsp;Arkabrata Bhattacharya,&nbsp;S P Duttagupta,&nbsp;Shriganesh S Prabhu","doi":"10.1007/s12043-024-02886-0","DOIUrl":"10.1007/s12043-024-02886-0","url":null,"abstract":"<div><p>Tera Hertz photoconductive antennas (THz PCAs) have significantly advanced the THz research by offering room-temperature operation, broad bandwidth and relatively low cost as both emitters and detectors. However, the primary limitation has been their low power output due to inefficient conversion. This article demonstrates a substantial improvement in efficiency (<span>(sim 200%)</span>) by incorporating sub-micron photonic structures on the surface. These photonic structures enhance pump beam coupling, leading to increased photocarrier generation. They also facilitate efficient carrier recombination after THz emission, thereby suppressing carrier screening. Experimental and numerical studies confirm the enhanced photocarrier generation and controlled transport through defect-free paths, further reducing screening effects. The integration of photonic structures into large area emitters (LAEs) holds the potential to develop emitters and detectors suitable for real-world THz systems, overcoming the limitations of the current commercial LAEs that rely on plasmonic structures or antireflection coatings. This innovation has the potential to revolutionise THz technology, enabling the development of more powerful and efficient THz sources and detectors. This can lead to advancements in various fields, including wireless communication, imaging and sensing and spectroscopy.</p></div>","PeriodicalId":743,"journal":{"name":"Pramana","volume":"99 1","pages":""},"PeriodicalIF":1.9,"publicationDate":"2025-02-04","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143107966","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}