The European Physical Journal B最新文献

{"title":"Doping and temperature dependence of pairing correlations in the two-dimensional Hubbard model: a determinant quantum Monte Carlo study","authors":"Saptarshi Ghosh","doi":"10.1140/epjb/s10051-026-01197-0","DOIUrl":"10.1140/epjb/s10051-026-01197-0","url":null,"abstract":"<p>We investigate superconducting pairing correlations in the doped two-dimensional Hubbard model using determinant quantum Monte Carlo simulations at intermediate coupling (<span>(U/t = 6)</span>). By systematically analyzing magnetic, vertex, symmetry-resolved, real-space, and finite-size pairing diagnostics as functions of doping and temperature, we obtain a coherent and cross-validated picture of interaction-driven pairing tendencies in the accessible parameter regime. We find that antiferromagnetic correlations are rapidly suppressed with hole doping, accompanied by a systematic enhancement of <i>d</i>-wave pairing correlations. The vertex contribution in the <i>d</i>-wave channel exhibits a crossover from negative to positive values upon doping, indicating a transition from an effectively repulsive to an attractive interaction. Symmetry-resolved analysis identifies the <i>d</i>-wave channel as the dominant interaction-driven pairing channel, while real-space correlations and finite-size scaling demonstrate that pairing remains short-ranged within the accessible temperatures and system sizes. The temperature dependence of pairing correlations reveals a nontrivial, non-monotonic interplay with doping, with enhanced pairing tendencies at intermediate doping levels. By combining vertex analysis, symmetry-resolved correlations, real-space behavior, and finite-size scaling within a unified framework, we provide a consistent cross-validation of interaction-driven pairing across multiple observables. Despite the enhancement of pairing correlations with decreasing temperature, no clear signatures of long-range superconducting order are observed. These results support a picture of interaction-driven <i>d</i>-wave pairing tendencies mediated by spin fluctuations and enhanced by hole doping, while highlighting the persistence of strong pairing fluctuations without long-range coherence in the accessible regime.</p>","PeriodicalId":787,"journal":{"name":"The European Physical Journal B","volume":"99 6","pages":""},"PeriodicalIF":1.9,"publicationDate":"2026-06-14","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"148281090","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":"Description using equilibrium temperature in the canonical ensemble within the framework of the Tsallis statistics employing the conventional expectation value","authors":"Masamichi Ishihara","doi":"10.1140/epjb/s10051-026-01180-9","DOIUrl":"10.1140/epjb/s10051-026-01180-9","url":null,"abstract":"<p>We studied the thermodynamic quantities and the probability distribution, expressing the probability distribution as a function of the energy, in the canonical ensemble within the framework of the Tsallis statistics, which is characterized by the entropic parameter <i>q</i>, employing the conventional expectation value (the linear average). We treated the power-law-like distribution. The equilibrium temperature, which is often called the physical temperature, was employed, and the probability distribution expressed in terms of the equilibrium temperature was derived. The Tsallis statistics expressed in terms of the equilibrium temperature was applied to <i>N</i> harmonic oscillators, where <i>N</i> is the number of the oscillators. The expressions of the energy, the Tsallis entropy, and the heat capacity were obtained. The expressions of these quantities and the expression of the probability distribution were obtained when the differences between adjacent energy levels are the same. These quantities and the distributions were numerically calculated. The <i>q</i> dependences of the energy, the Rényi entropy, and the heat capacity are weak. In contrast, the Tsallis entropy depends on <i>q</i>. The probability distribution as a function of the energy depends on <i>N</i> and <i>q</i>. The results provide a basis for describing power-law-like phenomena in the Tsallis statistics. The present formulation is expected to apply to various phenomena, because the harmonic oscillator plays a fundamental role in describing classical and quantum systems.</p>","PeriodicalId":787,"journal":{"name":"The European Physical Journal B","volume":"99 6","pages":""},"PeriodicalIF":1.9,"publicationDate":"2026-06-14","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"148281089","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":"Fabrication of NiAl2O4/PANI advanced electrode for supercapacitor application","authors":"Muhammad Younis,&nbsp;M. Hasnain Qaisrani,&nbsp;Rubina Naz Qaisrani,&nbsp; Tania,&nbsp;Sarah A. Alsalhi,&nbsp;Abhinav Kumar,&nbsp;Rizwan Ul Hassan","doi":"10.1140/epjb/s10051-026-01189-0","DOIUrl":"10.1140/epjb/s10051-026-01189-0","url":null,"abstract":"<div><p>One of the biggest challenges today is ensuring the development of efficient and sustainable energy storage technology. The best energy storage technology is the supercapacitor (SC), which can deliver and store large amounts of energy. Improving electrochemical performance is a key and heavily studied issue related to electrode materials. The electrochemical tests were conducted in a basic solution (3.0 M KOH) and NiAl₂O₄/PANI nanocomposite achieved a higher specific capacitance (<i>C</i>_s) of 935.28 F g⁻¹ at 1 A g⁻¹, while NiAl₂O₄ showed a lower <i>C</i>_s of 593.04 F g⁻¹. Additionally, the nanocomposite demonstrated good stability after 5000th cycles and showed increased energy density (E_d) of 29.80 Wh kg⁻¹ and power density (<i>P</i>_d) of 239.5 W kg⁻¹. Furthermore, the NiAl₂O₄/PANI demonstrated excellent electronic conductivity with a solution resistance (<i>R</i>_s) of 1.18 Ω. Compared to NiAl₂O₄, NiAl₂O₄/PANI offers improved electrochemical performance due to its larger surface area, lower resistance, and faster ion transfer within the electrolyte. Consequently, the NiAl₂O₄/PANI material developed here can be used in energy conversion technologies, supercapacitor electrodes, and energy storage systems in future.</p><h3>Graphical abstract</h3><div><figure><div><div><picture><source><img></source></picture><span>The alternative text for this image may have been generated using AI.</span></div></div></figure></div></div>","PeriodicalId":787,"journal":{"name":"The European Physical Journal B","volume":"99 6","pages":""},"PeriodicalIF":1.7,"publicationDate":"2026-06-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://link.springer.com/content/pdf/10.1140/epjb/s10051-026-01189-0.pdf","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"148236514","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Comprehensive insights into the structural, elastic, mechanical, thermoelectric, and optoelectronic properties of Ga- and In-based halide double perovskites Rb2AgMBr6 (M = Ga, In) semiconductors for advanced renewable energy applications","authors":"M. Musa Saad H.-E.,&nbsp;B. O. Alsobhi,&nbsp;A. Almeshal","doi":"10.1140/epjb/s10051-026-01187-2","DOIUrl":"10.1140/epjb/s10051-026-01187-2","url":null,"abstract":"<div><p>The growing demand for environmentally friendly and efficient materials for renewable energy applications has stimulated extensive research on lead-free halide double perovskites. In this work, the structural, electronic, elastic, mechanical, optical, and thermoelectric properties of inorganic double perovskites Rb₂AgMBr₆ (M = Ga, In) are systematically investigated using first-principles calculations. The optoelectronic structures are examined using generalized gradient approximation proposed by Perdew–Burke–Ernzerhof and the modified Becke–Johnson potential to obtain reliable band-gap predictions. The results reveal that both Rb₂AgMBr₆ compounds crystallize in a stable cubic crystal structure with space group Fm-3m and satisfy criteria for mechanical and thermodynamic stability. The calculated band structures confirm direct semiconducting behavior, with band-gap values significantly improved when using the modified Becke–Johnson potential, reaching 1.520 eV for Ga-based and 2.138 eV for In-based compounds. These values indicate strong suitability of Rb₂AgMBr₆ materials for optoelectronic applications. Elastic and mechanical analysis demonstrate that both materials are mechanically stable and exhibit ductile behavior. Optical properties show strong absorption in the visible and ultraviolet regions, along with high optical conductivity and low reflectivity and energy loss, highlighting their efficiency in light-harvesting applications. Furthermore, thermoelectric performance is notable, with figure of merit values approaching unity (<span>(ZT)</span> = 0.987 and 0.999), indicating high efficiency for energy conversion. Overall, the study demonstrates that Rb₂AgMBr₆ (M = Ga, In) double perovskites are stable, non-toxic semiconductors with excellent optoelectronic and thermoelectric properties, making them promising candidates for advanced renewable energy technologies.</p><h3>Graphical abstract</h3>\u0000<div><figure><div><div><picture><source><img></source></picture><span>The alternative text for this image may have been generated using AI.</span></div></div></figure></div></div>","PeriodicalId":787,"journal":{"name":"The European Physical Journal B","volume":"99 6","pages":""},"PeriodicalIF":1.7,"publicationDate":"2026-06-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"148236441","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":"Non-Markovian to Markovian transition in a driven single-site Holstein model","authors":"Chen-Huan Wu","doi":"10.1140/epjb/s10051-026-01183-6","DOIUrl":"10.1140/epjb/s10051-026-01183-6","url":null,"abstract":"<p>We investigate the non-adiabatic dynamics of the Holstein mechanism in a single-site model driven by a time-dependent perturbation. Unlike standard quenching protocols, we consider a unitary evolution where the driving field introduces a time-dependent displacement to the boson operators. The resulting dynamics reveal a dynamical quantum transition, evidenced by a distinct crossover from short-time non-Markovian behavior (characterized by power-law decay) to long-time Markovian-like behavior (exponential decay). This transition is consistently manifested in the polaronic shift, bosonic energy, and the population dynamics of the reduced density matrix. Furthermore, we analyze the emergence of effective non-unitary behavior. We demonstrate that while the global evolution remains unitary, the emergence of a degenerate ground state manifold at long times acts as an effective environment. Under a finite resolution threshold, the resulting fluctuations and mixing outweigh the coherent dynamics, leading to an effective unitary-to-nonunitary transition characterized by high mixedness and entanglement.</p>","PeriodicalId":787,"journal":{"name":"The European Physical Journal B","volume":"99 6","pages":""},"PeriodicalIF":1.7,"publicationDate":"2026-06-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"148236671","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":"Active-absorbing phase transitions in the parallel minority game","authors":"Aryan Tyagi,&nbsp;Soumyajyoti Biswas,&nbsp;Anirban Chakraborti","doi":"10.1140/epjb/s10051-026-01185-4","DOIUrl":"10.1140/epjb/s10051-026-01185-4","url":null,"abstract":"<p>The parallel minority game (PMG) is a synchronous adaptive multi-agent model that exhibits active-absorbing transitions characteristic of non-equilibrium statistical systems. We perform a comprehensive numerical study of the PMG under two families of microscopic decision rules: (i) agents update their choices based on instantaneous population in their alternative choices, and (ii) threshold-based activation that activates agents movement only after overcrowding density crossing a threshold. We measure time-dependent and steady-state limits of activity <span>(A(t))</span>, overcrowding fraction <span>(F(t))</span> as functions of the control parameter <span>(g=N/D)</span>, where <span>(N)</span> is the number of agents and <span>(D)</span> is the total number of sites. Instantaneous rules display the usual mean-field active-absorbing transition scaling with <span>(beta approx 1.00)</span>, <span>(delta approx 0.5)</span>, and <span>(nu _{parallel }approx 2.0)</span>. Threshold rules, however, produce a distinct non-mean-field universality class with <span>(beta approx 0.75)</span> and a systematic failure of mean-field dynamical scaling. We show that thresholding acts as a relevant perturbation in terms of the universality class. The results highlight how minimal cognitive features at the agent level fundamentally alter large-scale critical behavior in socio-economic and active systems.</p>","PeriodicalId":787,"journal":{"name":"The European Physical Journal B","volume":"99 6","pages":""},"PeriodicalIF":1.7,"publicationDate":"2026-06-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"148172937","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":"Formulation of optical solitons and modulation stability of a dispersive Schrödinger–Hirota equation arising in ultrashort pulse propagation","authors":"Mati ur Rahman,&nbsp;Sonia Akram,&nbsp;Laila A. AL-Essa","doi":"10.1140/epjb/s10051-026-01177-4","DOIUrl":"10.1140/epjb/s10051-026-01177-4","url":null,"abstract":"<p>This work negotiates an analytical investigation of nonlinear wave propagation governed by the dispersive Schrödinger–Hirota equation with parabolic-law nonlinearity, which arises naturally in the modeling of ultrashort optical pulse dynamics in nonlinear photonic media. By levering two efficient analytical approaches, namely the modified Sardar sub-equation (MSSE) method and the <span>(left( dfrac{mathscr {F}}{mu mathscr {F}+mathscr {G}}right) )</span>-expansion method, a wide range of optical soliton solutions is systematically developed. The derived solutions include bright, singular, dark, combo, periodic, bell-shaped, <i>M</i>-shaped, and mixed hyperbolic–trigonometric wave structures, emphasizing the richness of the model under different parametric regimes. To assess the physical relevance of the obtained solutions, a modulation instability (MI) analysis is carried out using the linear stability approach. The resulting dispersion relation and gain spectrum identify parameter regions where a continuous-wave background becomes unstable, thereby offering insight into the mechanisms responsible for soliton generation and nonlinear energy localization. The influence of key system parameters on wave dynamics is further demonstrated through graphical simulations, offering a clear visualization of solution structures and stability features. The combined analytical and dynamical results highlight that the governed model supports diverse nonlinear wave phenomena with strong applicability to modern waveguides, optical fibers, and photonic crystal structures. Therefore, this study enriches the analytical solution landscape of the dispersive Schrödinger–Hirota framework and contributes valuable theoretical insights relevant to ultrafast photonics, nonlinear optics, and optical communication technologies.</p>","PeriodicalId":787,"journal":{"name":"The European Physical Journal B","volume":"99 6","pages":""},"PeriodicalIF":1.7,"publicationDate":"2026-06-03","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"148172377","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":"Impurity and confinement effects on excitonic states in GaAs quantum dots: optical and transition properties","authors":"Suruchi Singh,&nbsp;Kapil Kumar,&nbsp;V. Bhasker Raj,&nbsp;Vinod Prasad,&nbsp;Savita Sharma,&nbsp; Varsha","doi":"10.1140/epjb/s10051-026-01182-7","DOIUrl":"10.1140/epjb/s10051-026-01182-7","url":null,"abstract":"<p>Quantum dots are widely studied because their optical properties can be tuned by varying their size and doping. In this work, we theoretically investigate the effect of centrally located donor and acceptor impurities on excitonic transitions in spherical Gallium Arsenide (GaAs) quantum dots. The nine-point finite difference method (FDM) is employed to calculate excitonic energies, binding energies, radial probability densities, oscillator strengths, and optical properties for different quantum dot radii and confinement regimes. The results show that impurity effects are most pronounced for the ground state, with the binding energy increasing for donor impurities and decreasing for acceptor impurities as the impurity charge <i>Z</i> varies. The oscillator strength is maximum for the 1s → 1p transition, while higher excited transitions show weaker strengths. In addition, the optical absorption peaks display noticeable blueshifts with increasing donor impurity strength under both strong and weak confinement regimes.</p>","PeriodicalId":787,"journal":{"name":"The European Physical Journal B","volume":"99 6","pages":""},"PeriodicalIF":1.7,"publicationDate":"2026-06-02","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"148172138","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":"Broadband tunable and controllably switchable optical power limiting in graphene waveguide ring resonators with the inverse Faraday effect-related nonlinearity","authors":"Hyon-A Kim,&nbsp;Yu-Song Pae,&nbsp;Chang-Bok Won,&nbsp;Nam-Hyon Pak,&nbsp;Ji-Song Pae,&nbsp;Song-Jin Im,&nbsp;Chol-Song Ri,&nbsp;Kum-Song Ho,&nbsp;Yong-Ha Han","doi":"10.1140/epjb/s10051-026-01181-8","DOIUrl":"10.1140/epjb/s10051-026-01181-8","url":null,"abstract":"<p>Optical power limiters are devices that are widely used to protect optical detectors from excessively high intensities of input light. They are particularly important for highly sensitive infrared sensors which are highly weak to be damaged from laser radiation. In this paper, we present optical power limiting in graphene waveguide ring resonators with the inverse Faraday effect-related nonlinearity in the mid-infrared frequency range. The resonance frequency and the coupling between the resonator and waveguide are strongly dependent on the chemical potentials of graphene. Our graphene plasmonic device can switch from the transmission of weak pulses to the transmission of strong pulses or vice versa for some purposes by controlling the gate voltages of the rolling graphene and planar sheets. And it can also provide broadband tunability of optical power limiting. Our suggested nonlinear device will have great potential usefulness to provide optical dynamic range compression and noise suppression in signal processing as well as protecting sensitive sensors</p>","PeriodicalId":787,"journal":{"name":"The European Physical Journal B","volume":"99 6","pages":""},"PeriodicalIF":1.7,"publicationDate":"2026-06-02","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"148172139","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":"Dynamical quantum phase transition in the non-Hermitian generalized Su–Schrieffer–Heeger model","authors":"Jiawen Yao,&nbsp;Ruohan Zhang,&nbsp;Siyuan Cheng,&nbsp;Zhengling Wang,&nbsp;Haoran Gu","doi":"10.1140/epjb/s10051-026-01186-3","DOIUrl":"10.1140/epjb/s10051-026-01186-3","url":null,"abstract":"<p>Based on the biorthogonal basis, we introduce the associated state and construct a more comprehensive framework for investigating biorthogonal dynamical quantum phase transitions in non-Hermitian systems. Taking the non-Hermitian Su–Schrieffer–Heeger model as an example, we characterize the distinct phase transition processes by virtue of the Loschmidt rate, dynamical topological order parameter, and Fisher zeros. We find that the key difference between biorthogonal case and self-normal case lies in the fact that the dynamical topological order parameter undergoes a half-integer jump in the biorthogonal case, which does not occur in the self-normal case. In addition, we discover that the periodicity of biorthogonal dynamical quantum phase transition is closely correlated with the oscillatory or stationary states of the two-level system at the critical momentum.</p>","PeriodicalId":787,"journal":{"name":"The European Physical Journal B","volume":"99 6","pages":""},"PeriodicalIF":1.7,"publicationDate":"2026-06-02","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"148104217","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}