Pub Date : 2026-01-07DOI: 10.1140/epjb/s10051-025-01114-x
Pelin Kavak
Over the past decade, perovskite solar cells have garnered significant attention owing to their exceptional optoelectronic properties. The performance of perovskite solar cells is highly dependent on the efficient operation of both hole transport layers and electron transport layers, making the selection of cost-effective and compatible charge transport materials critically important. Phenyl-C61-butyric acid methyl ester (PCBM) is widely utilized as an electron transport layer (ETL) in perovskite solar cells; however, several limitations persist, including low electron mobility, challenges in the deposition of uniform and high-quality films, and considerable interfacial recombination losses. In this study, potassium iodide (KI) doping of PCBM was investigated to enhance the photovoltaic parameters of perovskite solar cells. The incorporation of KI was found to enhance photovoltaic performance by optimizing surface morphology. Characterization techniques such as space charge limited current (SCLC) measurements confirmed a decrease in trap-state density within the perovskite layer, thereby mitigating charge recombination and contributing to improved device efficiency.
{"title":"Modification of PCBM electron transport layer (ETL) by potassium iodide in inverted type perovskite solar cells","authors":"Pelin Kavak","doi":"10.1140/epjb/s10051-025-01114-x","DOIUrl":"10.1140/epjb/s10051-025-01114-x","url":null,"abstract":"<div><p>Over the past decade, perovskite solar cells have garnered significant attention owing to their exceptional optoelectronic properties. The performance of perovskite solar cells is highly dependent on the efficient operation of both hole transport layers and electron transport layers, making the selection of cost-effective and compatible charge transport materials critically important. Phenyl-C<sub>61</sub>-butyric acid methyl ester (PCBM) is widely utilized as an electron transport layer (ETL) in perovskite solar cells; however, several limitations persist, including low electron mobility, challenges in the deposition of uniform and high-quality films, and considerable interfacial recombination losses. In this study, potassium iodide (KI) doping of PCBM was investigated to enhance the photovoltaic parameters of perovskite solar cells. The incorporation of KI was found to enhance photovoltaic performance by optimizing surface morphology. Characterization techniques such as space charge limited current (SCLC) measurements confirmed a decrease in trap-state density within the perovskite layer, thereby mitigating charge recombination and contributing to improved device efficiency.</p><h3>Graphical abstract</h3><p>Device fabrication under ambient air</p><div><figure><div><div><picture><source><img></source></picture></div></div></figure></div></div>","PeriodicalId":787,"journal":{"name":"The European Physical Journal B","volume":"99 1","pages":""},"PeriodicalIF":1.7,"publicationDate":"2026-01-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145909025","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}
Pub Date : 2026-01-07DOI: 10.1140/epjb/s10051-025-01092-0
Gengyao Li, Chao Li, Ying Xin, Bin Li
High-temperature superconducting (HTS) magnets are promising in high-field applications. However, due to inevitable joint resistance, HTS magnets still face challenges in maintaining a persistent current in their closed-loop operation. HTS flux pumps are devices that can charge closed HTS magnets wirelessly in the way of electromagnetic coupling. Thus, high-capacity DC power supplies and thick resistive current leads, which are generally used for charging superconducting magnets, can be replaced by HTS flux pumps. Hence, on the one hand, the extra heat load caused by the resistive current leads are avoided, improving the safety operation of HTS magnets. On the other hand, the cost of charging HTS magnets can be reduced. In this review, published works about HTS flux pumps and dynamic resistance are summarized. These studies have laid a foundation for the follow-up researches of flux pumps applied in high-field HTS magnets.
{"title":"Superconducting flux pumping for the high-field HTS magnet: the state of the art","authors":"Gengyao Li, Chao Li, Ying Xin, Bin Li","doi":"10.1140/epjb/s10051-025-01092-0","DOIUrl":"10.1140/epjb/s10051-025-01092-0","url":null,"abstract":"<div><p>High-temperature superconducting (HTS) magnets are promising in high-field applications. However, due to inevitable joint resistance, HTS magnets still face challenges in maintaining a persistent current in their closed-loop operation. HTS flux pumps are devices that can charge closed HTS magnets wirelessly in the way of electromagnetic coupling. Thus, high-capacity DC power supplies and thick resistive current leads, which are generally used for charging superconducting magnets, can be replaced by HTS flux pumps. Hence, on the one hand, the extra heat load caused by the resistive current leads are avoided, improving the safety operation of HTS magnets. On the other hand, the cost of charging HTS magnets can be reduced. In this review, published works about HTS flux pumps and dynamic resistance are summarized. These studies have laid a foundation for the follow-up researches of flux pumps applied in high-field HTS magnets.</p><h3>Graphical abstract</h3>\u0000<div><figure><div><div><picture><source><img></source></picture></div></div></figure></div></div>","PeriodicalId":787,"journal":{"name":"The European Physical Journal B","volume":"99 1","pages":""},"PeriodicalIF":1.7,"publicationDate":"2026-01-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145909023","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}
Pub Date : 2026-01-07DOI: 10.1140/epjb/s10051-025-01110-1
Kai Chen, Han Jiang
In this paper, we constructed a mathematical model of deep cellular crystal growth under anisotropic surface tension and anisotropic interface kinetics during directional solidification. Using the multivariate expansion method and the matched asymptotic expansion method, the dispersion relation of the rate of change of the perturbation amplitude at the deep cellular crystal interface and the quantization condition of the interface morphology are deduced, analyzed the stability of the growth of deep cellular crystal under the influence of anisotropic surface tension and anisotropic interface kinetics in the directional solidification, and revealed the influence of anisotropic parameters on the size of the unstable region. The results show that in the directional solidification considering anisotropic surface tension and anisotropic interface kinetics, there are two overall instability mechanisms for the morphology of deep cellular crystal growth interfaces: global oscillatory (GTW) instability and low-frequency (LF) instability. The stability analysis shows that the anisotropic surface tension and anisotropic interface kinetics have a significant effect on the global oscillatory instability mechanism in the low-order approximation. As the anisotropy parameter increases, the stable region of global oscillatory instability gradually expands. Relatively, the influence of the anisotropic interface kinetics parameter on the overall fluctuation instability of the interface morphology is more remarkable than the anisotropic surface tension parameter.
Graphical abstracts
These two images respectively depict the curves of the zeroth-order and first-order approximation GTW-S neutral modes under the influence of anisotropic surface tension parameters and anisotropic interface kinetics parameters. Comparison reveals that the critical stability parameter under the first-order approximation is smaller than that under the zeroth-order approximation. In both cases, the (n = 0) mode represents the most unstable state.
These two images display the curves of the first-order approximation GTW-S neutral modes for (n = 0). With increasing anisotropic parameters, the stable region associated with the overall oscillatory instability of highly oscillatory dendritic structures expands. The influence of the anisotropic interface kinetics parameter on the overall fluctuation instability of the interface morphology is more remarkable than the anisotropic surface tension parameter.
{"title":"Effect of anisotropy on the overall fluctuation instability of the interface morphology of deep cellular crystal","authors":"Kai Chen, Han Jiang","doi":"10.1140/epjb/s10051-025-01110-1","DOIUrl":"10.1140/epjb/s10051-025-01110-1","url":null,"abstract":"<div><p>In this paper, we constructed a mathematical model of deep cellular crystal growth under anisotropic surface tension and anisotropic interface kinetics during directional solidification. Using the multivariate expansion method and the matched asymptotic expansion method, the dispersion relation of the rate of change of the perturbation amplitude at the deep cellular crystal interface and the quantization condition of the interface morphology are deduced, analyzed the stability of the growth of deep cellular crystal under the influence of anisotropic surface tension and anisotropic interface kinetics in the directional solidification, and revealed the influence of anisotropic parameters on the size of the unstable region. The results show that in the directional solidification considering anisotropic surface tension and anisotropic interface kinetics, there are two overall instability mechanisms for the morphology of deep cellular crystal growth interfaces: global oscillatory (GTW) instability and low-frequency (LF) instability. The stability analysis shows that the anisotropic surface tension and anisotropic interface kinetics have a significant effect on the global oscillatory instability mechanism in the low-order approximation. As the anisotropy parameter increases, the stable region of global oscillatory instability gradually expands. Relatively, the influence of the anisotropic interface kinetics parameter on the overall fluctuation instability of the interface morphology is more remarkable than the anisotropic surface tension parameter.</p><h3>Graphical abstracts</h3><div><figure><div><div><picture><img></picture></div></div></figure></div><p>These two images respectively depict the curves of the zeroth-order and first-order approximation GTW-S neutral modes under the influence of anisotropic surface tension parameters and anisotropic interface kinetics parameters. Comparison reveals that the critical stability parameter under the first-order approximation is smaller than that under the zeroth-order approximation. In both cases, the <span>(n = 0)</span> mode represents the most unstable state.</p><div><figure><div><div><picture><img></picture></div></div></figure></div><p>These two images display the curves of the first-order approximation GTW-S neutral modes for <span>(n = 0)</span>. With increasing anisotropic parameters, the stable region associated with the overall oscillatory instability of highly oscillatory dendritic structures expands. The influence of the anisotropic interface kinetics parameter on the overall fluctuation instability of the interface morphology is more remarkable than the anisotropic surface tension parameter.</p></div>","PeriodicalId":787,"journal":{"name":"The European Physical Journal B","volume":"99 1","pages":""},"PeriodicalIF":1.7,"publicationDate":"2026-01-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145909026","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}
Pub Date : 2026-01-07DOI: 10.1140/epjb/s10051-025-01106-x
V. Vijayalakshmi, G. Suresh, S. Selvakumari, V. Ragavendran, J. Janczak, N. Kanagathara
Single crystals of Piperazinium Nitrate were obtained by slow evaporation, crystallizing in a monoclinic system (P21/c), and stabilized by strong N–H···O hydrogen bonds in a three-dimensional network. structural integrity of the grown crystal was confirmed by X-ray diffraction (XRD) analysis. Experimental characterization using FT–IR and FT–Raman spectroscopy confirmed the presence of functional groups and characteristic vibrational modes corresponding to the molecular structure. Hirshfeld surface (HS) analysis and 2D fingerprint plots quantified the intermolecular contacts, highlighting the dominant role of hydrogen bonding in crystal packing and structural stability. HS analysis revealed that O···H interactions contribute 54.9% of the overall intermolecular contacts, confirming the dominance of hydrogen bonding in the crystal packing. Density Functional Theory (DFT) calculations at the B3LYP/6-311G (d, p) level were performed to optimize the molecular geometry and investigate the electronic structure, revealing a significant HOMO–LUMO energy gap of 5.391 eV, denoting the stability of molecule and low chemical reactivity. Time-Dependent DFT (TD-DFT) simulations of the UV–Visible (UV–Vis) spectrum provided insights into the electronic excitation behavior. The absorption peak at 255.76 nm, it exhibits the π → π* and n → π* electronic transitions in gas phase. Natural Bond Orbital (NBO) analysis indicated a strong intramolecular hyperconjugative interaction between the lone pair on LP(3) O2 and antibonding orbital of the N1–O4 bond, contributing 144.41 kJ mol−1 to molecular stabilization. Fukui function analysis identified the reactive sites susceptible to electrophilic and nucleophilic attack. Electron Localization Function (ELF) and Localized Orbital Locator (LOL) maps illustrated regions of electron localization and delocalization. Non-Covalent Interaction (NCI) analysis based on Reduced Density Gradient (RDG) plots revealed the presence of weak van der Waals forces and strong hydrogen bonding interactions. The calculated first-order hyperpolarizability (29.244 × 10⁻31 esu), which is 7.8 times greater than that of urea, and the calculated first-order hyperpolarizability confirms the strong NLO response and highlights the potential of the compound for nonlinear optical (NLO) and photonic applications.
{"title":"Quantum chemical exploration of piperazinium nitrate: molecular stability, reactivity descriptors, electronic excitations, intermolecular interactions, and NLO activity","authors":"V. Vijayalakshmi, G. Suresh, S. Selvakumari, V. Ragavendran, J. Janczak, N. Kanagathara","doi":"10.1140/epjb/s10051-025-01106-x","DOIUrl":"10.1140/epjb/s10051-025-01106-x","url":null,"abstract":"<div><p>Single crystals of Piperazinium Nitrate were obtained by slow evaporation, crystallizing in a monoclinic system (P2<sub>1</sub>/<i>c</i>), and stabilized by strong N–H···O hydrogen bonds in a three-dimensional network. structural integrity of the grown crystal was confirmed by X-ray diffraction (XRD) analysis. Experimental characterization using FT–IR and FT–Raman spectroscopy confirmed the presence of functional groups and characteristic vibrational modes corresponding to the molecular structure. Hirshfeld surface (HS) analysis and 2D fingerprint plots quantified the intermolecular contacts, highlighting the dominant role of hydrogen bonding in crystal packing and structural stability. HS analysis revealed that O···H interactions contribute 54.9% of the overall intermolecular contacts, confirming the dominance of hydrogen bonding in the crystal packing. Density Functional Theory (DFT) calculations at the B3LYP/6-311G (d, p) level were performed to optimize the molecular geometry and investigate the electronic structure, revealing a significant HOMO–LUMO energy gap of 5.391 eV, denoting the stability of molecule and low chemical reactivity. Time-Dependent DFT (TD-DFT) simulations of the UV–Visible (UV–Vis) spectrum provided insights into the electronic excitation behavior. The absorption peak at 255.76 nm, it exhibits the π → π* and n → π* electronic transitions in gas phase. Natural Bond Orbital (NBO) analysis indicated a strong intramolecular hyperconjugative interaction between the lone pair on LP(3) O<sub>2</sub> and antibonding orbital of the N1–O4 bond, contributing 144.41 kJ mol<sup>−1</sup> to molecular stabilization. Fukui function analysis identified the reactive sites susceptible to electrophilic and nucleophilic attack. Electron Localization Function (ELF) and Localized Orbital Locator (LOL) maps illustrated regions of electron localization and delocalization. Non-Covalent Interaction (NCI) analysis based on Reduced Density Gradient (RDG) plots revealed the presence of weak van der Waals forces and strong hydrogen bonding interactions. The calculated first-order hyperpolarizability (29.244 × 10⁻<sup>31</sup> esu), which is 7.8 times greater than that of urea, and the calculated first-order hyperpolarizability confirms the strong NLO response and highlights the potential of the compound for nonlinear optical (NLO) and photonic applications.</p><h3>Graphical abstract</h3>\u0000<div><figure><div><div><picture><source><img></source></picture></div></div></figure></div></div>","PeriodicalId":787,"journal":{"name":"The European Physical Journal B","volume":"99 1","pages":""},"PeriodicalIF":1.7,"publicationDate":"2026-01-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145909024","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}
Pub Date : 2025-12-26DOI: 10.1140/epjb/s10051-025-01115-w
Ishita Tikader, Muktish Acharyya
The transient behaviours of a Blume–Capel ferromagnetic needle have been studied extensively by Monte-Carlo simulation. The needle has an elongated length in one direction compared to its cross-section. In the context of transient behaviour, we have captured the decay of the metastable state and the magnetic relaxation behaviours in our study. The dependence of metastable behaviour on anisotropy (single site) has been studied. Interestingly, we have observed multiple (different values ofnin different time domains) crossover in the decay of metastable volume fraction (obeying Avrami’s law(beta sim textrm{exp}(-Kt^n))). We have identified the crossover time, and the values ofnare estimated precisely. The mean (magnetic) reversal time has been studied as a function of anisotropy. It is observed to be almost independent of anisotropy for its negative value; however, it is found to decrease exponentially with positive anisotropy. The exponential relaxation behaviour (in the corresponding paramagnetic phase) is observed. The relaxation time was found to depend on the strength of anisotropy.
{"title":"Multiple crossover in the decay of metastable volume fraction of a Blume–Capel ferromagnetic needle","authors":"Ishita Tikader, Muktish Acharyya","doi":"10.1140/epjb/s10051-025-01115-w","DOIUrl":"10.1140/epjb/s10051-025-01115-w","url":null,"abstract":"<p>The transient behaviours of a Blume–Capel ferromagnetic needle have been studied extensively by Monte-Carlo simulation. The needle has an elongated length in one direction compared to its cross-section. In the context of transient behaviour, we have captured the decay of the metastable state and the magnetic relaxation behaviours in our study. The dependence of metastable behaviour on anisotropy (single site) has been studied. <i>Interestingly, we have observed multiple</i> (<i>different values of</i> <i>n</i> <i>in different time domains</i>) <i>crossover in the decay of metastable volume fraction</i> (<i>obeying Avrami’s law</i> <span>(beta sim textrm{exp}(-Kt^n))</span>). <i>We have identified the crossover time, and the values of</i> <i>n</i> <i>are estimated precisely.</i> The mean (magnetic) reversal time has been studied as a function of anisotropy. It is observed to be almost independent of anisotropy for its negative value; however, it is found to decrease exponentially with positive anisotropy. The exponential relaxation behaviour (in the corresponding paramagnetic phase) is observed. The relaxation time was found to depend on the strength of anisotropy.</p>","PeriodicalId":787,"journal":{"name":"The European Physical Journal B","volume":"98 12","pages":""},"PeriodicalIF":1.7,"publicationDate":"2025-12-26","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145831336","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}
Pub Date : 2025-12-24DOI: 10.1140/epjb/s10051-025-01111-0
D. S. Lohr-Robles, M. Grether, E. López-Moreno, P. O. Hess
The dynamical properties of the Lipkin–Meshkov–Glick model with longitudinal and transverse fields are studied by considering quantum quenches. The model describes a many-body quantum system with long-range interactions. A semiclassical analysis is performed to obtain the critical points of quantum phase transitions. These critical points consist in the static separatrix, which is found by analyzing the stability structure of the semiclassical potential and is useful in the identification of ground state and excited states quantum phase transitions, and in the dynamical separatrix, which depends on initial conditions and is found by studying the classical equations of motion for the Hamiltonian. The static and dynamical separatrices divide the parameter space in regions of different dynamical behavior, and it is found that both separatrices play an important role in the determination of the occurrences of the dynamical quantum phase transitions.
{"title":"Dynamical quantum phase transitions in the Lipkin–Meshkov–Glick model with longitudinal and transverse magnetic fields","authors":"D. S. Lohr-Robles, M. Grether, E. López-Moreno, P. O. Hess","doi":"10.1140/epjb/s10051-025-01111-0","DOIUrl":"10.1140/epjb/s10051-025-01111-0","url":null,"abstract":"<p>The dynamical properties of the Lipkin–Meshkov–Glick model with longitudinal and transverse fields are studied by considering quantum quenches. The model describes a many-body quantum system with long-range interactions. A semiclassical analysis is performed to obtain the critical points of quantum phase transitions. These critical points consist in the static separatrix, which is found by analyzing the stability structure of the semiclassical potential and is useful in the identification of ground state and excited states quantum phase transitions, and in the dynamical separatrix, which depends on initial conditions and is found by studying the classical equations of motion for the Hamiltonian. The static and dynamical separatrices divide the parameter space in regions of different dynamical behavior, and it is found that both separatrices play an important role in the determination of the occurrences of the dynamical quantum phase transitions.</p>","PeriodicalId":787,"journal":{"name":"The European Physical Journal B","volume":"98 12","pages":""},"PeriodicalIF":1.7,"publicationDate":"2025-12-24","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://link.springer.com/content/pdf/10.1140/epjb/s10051-025-01111-0.pdf","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145831510","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}
Pub Date : 2025-12-23DOI: 10.1140/epjb/s10051-025-01112-z
Rahul Chhimpa, Avinash Chand Yadav
We propose a simple model for a sample space reducing (SSR) stochastic process, where the dynamical variable denoting the size of the state space is continuous. In general, one can view the model as a constrained multiplicative stochastic process such that the size of the state space cannot be smaller than a visibility parameter (epsilon .) We study the survival time statistics that reveal a subtle difference from the discrete version of the process. A straightforward generalization can explain the noisy SSR process, characterized by a tunable parameter (lambda in [0, 1].) We also examine the statistics of the size of the state space that follows a power-law distributed probability ({mathbb {P}}_{epsilon }(zle epsilon ) sim z^{-alpha },) with a nontrivial value of the exponent as a function of the tunable parameter (alpha = 1+lambda .)
{"title":"Continuous sample space reducing stochastic process","authors":"Rahul Chhimpa, Avinash Chand Yadav","doi":"10.1140/epjb/s10051-025-01112-z","DOIUrl":"10.1140/epjb/s10051-025-01112-z","url":null,"abstract":"<p>We propose a simple model for a sample space reducing (SSR) stochastic process, where the dynamical variable denoting the size of the state space is continuous. In general, one can view the model as a constrained multiplicative stochastic process such that the size of the state space cannot be smaller than a visibility parameter <span>(epsilon .)</span> We study the survival time statistics that reveal a subtle difference from the discrete version of the process. A straightforward generalization can explain the noisy SSR process, characterized by a tunable parameter <span>(lambda in [0, 1].)</span> We also examine the statistics of the size of the state space that follows a power-law distributed probability <span>({mathbb {P}}_{epsilon }(zle epsilon ) sim z^{-alpha },)</span> with a nontrivial value of the exponent as a function of the tunable parameter <span>(alpha = 1+lambda .)</span></p>","PeriodicalId":787,"journal":{"name":"The European Physical Journal B","volume":"98 12","pages":""},"PeriodicalIF":1.7,"publicationDate":"2025-12-23","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145831447","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}
Pub Date : 2025-12-22DOI: 10.1140/epjb/s10051-025-01105-y
Vasanth Kumar Babu, Rahul Pandit
The Ising spin model has long been the foundational model for studying phase transitions in theoretical statistical physics. In the wake of the explosion of machine-learning (ML) techniques in recent years, the Ising model has been used for ML applications to phase transitions. In this overview, we discuss the applications of ML, via both supervised and unsupervised learning, to the study of phases and transitions in the Ising model. We also discuss transfer learning and provide some examples of its use for neural networks trained on Ising model spin configurations. We conclude with a summary and some future directions.
{"title":"Artificial intelligence and machine learning for phases and transitions in the Ising model: an overview","authors":"Vasanth Kumar Babu, Rahul Pandit","doi":"10.1140/epjb/s10051-025-01105-y","DOIUrl":"10.1140/epjb/s10051-025-01105-y","url":null,"abstract":"<p>The Ising spin model has long been the foundational model for studying phase transitions in theoretical statistical physics. In the wake of the explosion of machine-learning (ML) techniques in recent years, the Ising model has been used for ML applications to phase transitions. In this overview, we discuss the applications of ML, via both supervised and unsupervised learning, to the study of phases and transitions in the Ising model. We also discuss transfer learning and provide some examples of its use for neural networks trained on Ising model spin configurations. We conclude with a summary and some future directions.</p>","PeriodicalId":787,"journal":{"name":"The European Physical Journal B","volume":"98 12","pages":""},"PeriodicalIF":1.7,"publicationDate":"2025-12-22","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145831420","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}
Pub Date : 2025-12-17DOI: 10.1140/epjb/s10051-025-01088-w
Haifa A. Alyousef, Shaimaa A. M. Abdelmohsen, Areej Saleh Alqarny, Najla Alotaibi, Younis Ejaz, Muhammad Imran, Hafiz Muhammd Tahir Farid
The rapid progress of various renewable energy conversion methods has driven an increasing demand for efficient energy storage systems. Transition metal oxides are widely utilized as electrodes in supercapacitor devices; nonetheless, however, they suffer from significant drawbacks such as limited surface area and inadequate conductivity. Doping has been recognized as an efficient approach to overcome these limitations. This current research utilized a hydrothermal technique to increase the capacitive characteristics of CoMoO3 by doping with barium ion (Ba2+). Several physical studies were utilized to confirm the crystal structure, enhanced morphology and surface area of Ba-doped CoMoO3, while the physiochemical parameters of doped electrode sample were assessed using several analytical techniques. The examination of energy storage applications included a 3.0 M KOH for performing cyclic voltammetry (CV) studies, galvanic charge–discharge (GCD), and electrochemical impedance spectroscopy (EIS). Ba-doped CoMoO3 nanocomposites exhibit significant Cs values of approximately 1001 F/g with Ed of (20.48 Wh/kg) and Pd of (192 W/kg) showcasing superior charge–discharge cyclic performance. The Ba-doped CoMoO3 electrode material exhibited superior electrochemical properties, rendering it a viable candidate for future supercapacitor devices.
Graphical abstract
各种可再生能源转换方法的快速发展推动了对高效储能系统的需求不断增长。过渡金属氧化物作为电极广泛应用于超级电容器器件中；然而，它们也有明显的缺点，如表面积有限和导电性不足。兴奋剂已被认为是克服这些限制的有效方法。本研究利用水热技术通过掺杂钡离子（Ba2+）来提高CoMoO3的电容特性。利用多项物理研究证实了ba掺杂CoMoO3的晶体结构、增强形貌和表面积，同时利用多种分析技术对掺杂电极样品的理化参数进行了评估。对储能应用的研究包括3.0 M KOH，用于循环伏安法（CV）研究、原电充放电（GCD）和电化学阻抗谱（EIS）。ba掺杂CoMoO3纳米复合材料的Cs值约为1001 F/g， Ed为20.48 Wh/kg， Pd为192 W/kg，具有优异的充放电循环性能。ba掺杂的CoMoO3电极材料表现出优异的电化学性能，使其成为未来超级电容器器件的可行候选材料。图形抽象
{"title":"Enhanced electrochemical performance of Ba-doped CoMoO3 for supercapacitor applications","authors":"Haifa A. Alyousef, Shaimaa A. M. Abdelmohsen, Areej Saleh Alqarny, Najla Alotaibi, Younis Ejaz, Muhammad Imran, Hafiz Muhammd Tahir Farid","doi":"10.1140/epjb/s10051-025-01088-w","DOIUrl":"10.1140/epjb/s10051-025-01088-w","url":null,"abstract":"<div><p>The rapid progress of various renewable energy conversion methods has driven an increasing demand for efficient energy storage systems. Transition metal oxides are widely utilized as electrodes in supercapacitor devices; nonetheless, however, they suffer from significant drawbacks such as limited surface area and inadequate conductivity. Doping has been recognized as an efficient approach to overcome these limitations. This current research utilized a hydrothermal technique to increase the capacitive characteristics of CoMoO<sub>3</sub> by doping with barium ion (Ba<sup>2+</sup>). Several physical studies were utilized to confirm the crystal structure, enhanced morphology and surface area of Ba-doped CoMoO<sub>3</sub>, while the physiochemical parameters of doped electrode sample were assessed using several analytical techniques. The examination of energy storage applications included a 3.0 M KOH for performing cyclic voltammetry (CV) studies, galvanic charge–discharge (GCD), and electrochemical impedance spectroscopy (EIS). Ba-doped CoMoO<sub>3</sub> nanocomposites exhibit significant <i>C</i><sub>s</sub> values of approximately 1001 F/g with <i>E</i><sub>d</sub> of (20.48 Wh/kg) and <i>P</i><sub>d</sub> of (192 W/kg) showcasing superior charge–discharge cyclic performance. The Ba-doped CoMoO<sub>3</sub> electrode material exhibited superior electrochemical properties, rendering it a viable candidate for future supercapacitor devices.</p><h3>Graphical abstract</h3>\u0000<div><figure><div><div><picture><source><img></source></picture></div></div></figure></div></div>","PeriodicalId":787,"journal":{"name":"The European Physical Journal B","volume":"98 12","pages":""},"PeriodicalIF":1.7,"publicationDate":"2025-12-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145779028","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}
Pub Date : 2025-12-08DOI: 10.1140/epjb/s10051-025-01104-z
Bianca Y. S. Ishikawa, José F. Fontanari
The Inspection Game is the canonical model for the strategic conflict between law enforcement (inspectors) and citizens (potential criminals). Its classical Mixed-Strategy Nash Equilibrium (MSNE) is afflicted by a paradox: the equilibrium crime rate is independent of both the penalty size (p) and the crime gain (g), undermining the efficacy of deterrence policy. We re-examine this challenge using evolutionary game theory, focusing on the long-term fixation probabilities of strategies in finite, asymmetric population sizes subject to demographic noise. The deterministic limit of our model exhibits stable limit cycles around the MSNE, which coincides with the neutral fixed point of the equilibrium analysis. Crucially, in finite populations, demographic noise drives the system away from this cycle and toward absorbing states. Our results demonstrate that high absolute penalties p are highly effective at suppressing crime by influencing the geometry of the deterministic dynamics, which in turn biases the fixation probability toward the criminal extinction absorbing state, thereby restoring the intuitive role of p. Furthermore, we reveal a U-shaped policy landscape where both high penalties and light penalties (where (p approx g)) are successful suppressors, maximizing criminal risk at intermediate penalty levels. Most critically, we analyze the realistic asymptotic limit of extreme population sizes asymmetry, where inspectors are exceedingly rare. In this limit, the system’s dynamic outcome is entirely decoupled from the citizen payoff parameters p and g, and is instead determined by the initial frequency of crime relative to the deterrence threshold (the ratio of inspection cost to reward for catching a criminal). This highlights that effective crime suppression requires managing the interaction between deterministic dynamics, demographic noise, and initial conditions.
{"title":"Finite population dynamics resolve the central paradox of the Inspection Game","authors":"Bianca Y. S. Ishikawa, José F. Fontanari","doi":"10.1140/epjb/s10051-025-01104-z","DOIUrl":"10.1140/epjb/s10051-025-01104-z","url":null,"abstract":"<p>The Inspection Game is the canonical model for the strategic conflict between law enforcement (inspectors) and citizens (potential criminals). Its classical Mixed-Strategy Nash Equilibrium (MSNE) is afflicted by a paradox: the equilibrium crime rate is independent of both the penalty size (<i>p</i>) and the crime gain (<i>g</i>), undermining the efficacy of deterrence policy. We re-examine this challenge using evolutionary game theory, focusing on the long-term fixation probabilities of strategies in finite, asymmetric population sizes subject to demographic noise. The deterministic limit of our model exhibits stable limit cycles around the MSNE, which coincides with the neutral fixed point of the equilibrium analysis. Crucially, in finite populations, demographic noise drives the system away from this cycle and toward absorbing states. Our results demonstrate that high absolute penalties <i>p</i> are highly effective at suppressing crime by influencing the geometry of the deterministic dynamics, which in turn biases the fixation probability toward the criminal extinction absorbing state, thereby restoring the intuitive role of <i>p</i>. Furthermore, we reveal a U-shaped policy landscape where both high penalties and light penalties (where <span>(p approx g)</span>) are successful suppressors, maximizing criminal risk at intermediate penalty levels. Most critically, we analyze the realistic asymptotic limit of extreme population sizes asymmetry, where inspectors are exceedingly rare. In this limit, the system’s dynamic outcome is entirely decoupled from the citizen payoff parameters <i>p</i> and <i>g</i>, and is instead determined by the initial frequency of crime relative to the deterrence threshold (the ratio of inspection cost to reward for catching a criminal). This highlights that effective crime suppression requires managing the interaction between deterministic dynamics, demographic noise, and initial conditions.</p>","PeriodicalId":787,"journal":{"name":"The European Physical Journal B","volume":"98 12","pages":""},"PeriodicalIF":1.7,"publicationDate":"2025-12-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145729964","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}
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