The European Physical Journal B最新文献

{"title":"Nonlinear wave control in an alpha-helix proteins with an impurity: mechanisms of localization, trapping and transmission of breathers","authors":"R. Y. Ondoua,&nbsp;J. C. Mimshe Fewu,&nbsp;M. Youssoufa,&nbsp;R. Abouem A. Ribama,&nbsp;H. P. Ekobena Fouda,&nbsp;J. P. Nguenang,&nbsp;C. B. Tabi","doi":"10.1140/epjb/s10051-026-01194-3","DOIUrl":"10.1140/epjb/s10051-026-01194-3","url":null,"abstract":"<p>This paper studies a one-stranded <span>(alpha )</span>-helix of a protein chain in the presence of diagonal and off-diagonal couplings under the control of a mass impurity. Using the semi-discrete approximation and the multiple time scale method, we derive discrete and semi-discrete nonlinear Schrödinger equations. Through the phenomenon of modulational instability, the analysis of linear stability is carried out. A numerical analysis of modulational instability predicts the propagation of solitonic breather-like structures within the system under the simultaneous effect of the mass impurity and the off-diagonal coupling parameter. Furthermore, a numerical study of the impurity mode reveals that indeed the dynamics of the system is characterized by the propagation of solitary breather-like waves. Furthermore, our exploration of the interaction between the breather and the impurity mode reveals a series of physical phenomena, including trapping, reflection, and transmission. Finally, the localization associated with modulational instability in the <span>(alpha )</span>-helix is well described, aligning analytical predictions with numerical simulations.</p>","PeriodicalId":787,"journal":{"name":"The European Physical Journal B","volume":"99 6","pages":""},"PeriodicalIF":1.9,"publicationDate":"2026-06-29","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"148380905","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":"Finite-temperature antiferromagnetic correlations and doping effects in the square-lattice Hubbard model","authors":"Saptarshi Ghosh","doi":"10.1140/epjb/s10051-026-01199-y","DOIUrl":"10.1140/epjb/s10051-026-01199-y","url":null,"abstract":"<p>We investigate finite-temperature antiferromagnetic correlations in the two-dimensional square-lattice Hubbard model using determinant quantum Monte Carlo simulations. Magnetic properties are analyzed through the antiferromagnetic structure factor <span>(S(pi ,pi ))</span>, real-space spin correlations, correlation-length extraction, and finite-size scaling. At half filling, the antiferromagnetic structure factor increases strongly with inverse temperature for interaction strengths <span>(U=2)</span>–8, reflecting the rapid enhancement of staggered spin correlations upon cooling. Real-space correlations exhibit a clear staggered oscillatory structure with an approximately exponential decay. Semi-logarithmic analysis of the staggered correlations reveals a rapidly increasing effective correlation length <span>(xi _textrm{eff})</span> with decreasing temperature. For sufficiently low temperatures, <span>(xi _textrm{eff})</span> becomes comparable to the lattice size, indicating the onset of strong finite-size effects rather than true long-range order. Finite-size scaling of <span>(S(pi ,pi )/N)</span> shows a systematic suppression with increasing system size, consistent with the absence of finite-temperature long-range antiferromagnetic order in accordance with the Mermin–Wagner theorem. Upon doping away from half filling, both the momentum-space structure factor and the real-space staggered correlations are strongly suppressed. The extracted correlation length decreases substantially with doping, demonstrating that mobile carriers weaken the spatial extent of antiferromagnetic correlations. The suppression is observed for both hole and electron doping and is broadly consistent with particle–hole symmetry of the bipartite square lattice. The present results establish a unified finite-temperature picture linking magnetic structure factors, real-space spin correlations, correlation-length growth, and finite-size effects in the square-lattice Hubbard model. Benchmark comparisons with earlier numerical studies further demonstrate quantitative consistency with previously established finite-temperature magnetic trends in the two-dimensional Hubbard model.</p>","PeriodicalId":787,"journal":{"name":"The European Physical Journal B","volume":"99 6","pages":""},"PeriodicalIF":1.9,"publicationDate":"2026-06-29","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"148380844","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"First-principles study of the structural, electronic, magnetic, mechanical, phonon, and thermoelectric properties of the quaternary Heusler alloys CoVTiZ (Z = Ga, In)","authors":"Bishnu Chakraborty,&nbsp;T. K. Nath","doi":"10.1140/epjb/s10051-026-01200-8","DOIUrl":"10.1140/epjb/s10051-026-01200-8","url":null,"abstract":"<p>We present a first-principles investigation of CoVTiZ (Z = Ga, In) quaternary Heusler alloys to assess their potential as spin-gapless semiconductors and evaluate their multifunctional properties. We comprehensively investigate the structural, electronic, magnetic, mechanical, dynamical, and thermoelectric properties of these compounds using density functional theory. Our calculations reveal that both alloys exhibit thermodynamic stability with negative formation energies of − 1.178 eV/f.u. for CoVTiGa and − 0.168 eV/f.u. for CoVTiIn. The calculated energy above the convex hull per atom for both the compounds is approximately 0.1 eV/atom. Band structure and density of states analysis confirm that CoVTiIn exhibits ideal spin-gapless semiconducting behavior, while CoVTiGa demonstrates nearly spin-gapless characteristics. The total magnetic moments of 2.99 <span>(mu _B)</span> and 3.00 <span>(mu _B)</span> are consistent with the Slater–Pauling rule. Mechanical property analysis reveals that both compounds are mechanically stable and ductile, with CoVTiGa showing better hardness (9.43 GPa) and higher Debye temperature (470.0 K). Phonon dispersion calculations confirm dynamical stability with no negative frequencies. Thermoelectric calculations yield promising dimensionless figures of merit (<i>ZT</i>) ranging from 0.8 to 1.0 at elevated temperatures, particularly in n-type doping regions.</p>","PeriodicalId":787,"journal":{"name":"The European Physical Journal B","volume":"99 6","pages":""},"PeriodicalIF":1.9,"publicationDate":"2026-06-27","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"148323982","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":"Finite-time Lyapunov signatures of dynamical regimes in reservoir models","authors":"Dishant Sisodia,&nbsp;Sarika Jalan","doi":"10.1140/epjb/s10051-026-01204-4","DOIUrl":"10.1140/epjb/s10051-026-01204-4","url":null,"abstract":"<p>Although reservoir models are known to accurately predict critical transitions and regime changes, conventional analyses based on output time series or low-dimensional bifurcation structure fails to reveal the underlying mechanisms. This limitation arises because in high-dimensional reservoir space, qualitatively distinct pathways can yield similar outputs, obscuring the true nature of transitions. We show that finite-time Lyapunov exponent (FTLE) fills this gap by providing a dynamical measure sensitive to local stability within the reservoir. This is particularly crucial for transitions such as interior crises, where identifying collisions with unstable periodic orbits is practically infeasible in high dimensions. Using the logistic map as a canonical system, which apart from depicting interior crisis, exhibits intermittency, fully developed chaos, and crisis-induced transitions, we demonstrate that even when these regimes are not easily distinguishable in the reservoir state space using conventional methods, their FTLE distributions are faithfully reproduced. Our results establish FTLE as a systematic route to interpret high-dimensional reservoir models in terms of the underlying dynamical systems they emulate.</p>","PeriodicalId":787,"journal":{"name":"The European Physical Journal B","volume":"99 6","pages":""},"PeriodicalIF":1.9,"publicationDate":"2026-06-26","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"148323577","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":"Electronic structure and optical properties of Y-doped, Yb-doped, and Y–Yb Co-doped AlN: a first-principles study","authors":"Shiping Wang,&nbsp;Haixia Li,&nbsp;Jiacheng Liu","doi":"10.1140/epjb/s10051-026-01203-5","DOIUrl":"10.1140/epjb/s10051-026-01203-5","url":null,"abstract":"<div><p>Rare-earth-doped AlN is a promising material system for optoelectronic applications. In this work, first-principles calculations based on density functional theory are employed to investigate the electronic structures and optical properties of intrinsic AlN, Y-doped AlN, Yb-doped AlN, and AlN co-doped with Y and Yb. The effects of doping on lattice distortion, band-structure evolution, density of states, dielectric response, optical conductivity, absorption, and reflectivity are systematically analyzed. The results show that Y and Yb doping induces lattice expansion in AlN, and the expansion becomes more pronounced with increasing doping concentration. Doping also reduces the band gap, with the AlN: Y₂–Yb₂ model showing the smallest gap among the studied structures. The density-of-states results indicate that dopant-related states contribute near the Fermi level and modify the orbital distribution of the system. In addition, doping increases the static dielectric constant and shifts the low-energy optical response toward lower photon energies. Overall, Y and Yb doping alters the electronic structure and optical response of AlN under the present computational framework. These findings provide a theoretical basis for understanding rare-earth-doping effects on the electronic and optical properties of AlN.</p><h3>Graphical abstract</h3><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 6","pages":""},"PeriodicalIF":1.9,"publicationDate":"2026-06-26","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"148323585","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":"Thermodynamic signatures of lthe Aharonov–Bohm effect in monolayer and bilayer graphene rings","authors":"Boubakeur Khantoul,&nbsp;Ahmed Tedjani","doi":"10.1140/epjb/s10051-026-01193-4","DOIUrl":"10.1140/epjb/s10051-026-01193-4","url":null,"abstract":"<p>We develop a thermodynamic theory of the Aharonov–Bohm effect in monolayer and bilayer graphene rings based on a regularized grand canonical formalism. We show that the distinct band structures produce qualitatively different responses: monolayer graphene exhibits multi-harmonic persistent currents with slow algebraic decay, while bilayer graphene is dominated by a single harmonic due to rapid suppression of higher-order contributions. These differences persist at finite temperature and are reflected in the heat capacity, which is linear in temperature for monolayer and exhibits a Schottky-like feature for bilayer. Our results establish thermodynamic measurements as a direct probe of band structure and quasiparticle dynamics in graphene nanostructures.</p>","PeriodicalId":787,"journal":{"name":"The European Physical Journal B","volume":"99 6","pages":""},"PeriodicalIF":1.9,"publicationDate":"2026-06-24","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"148323147","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":"Critical temperature(s) of Sierpiński carpet(s)","authors":"R. Ben Alì Zinati,&nbsp;G. Gori,&nbsp;A. Codello","doi":"10.1140/epjb/s10051-026-01196-1","DOIUrl":"10.1140/epjb/s10051-026-01196-1","url":null,"abstract":"<p>We present a key algorithmic improvement to the generalized combinatorial Feynman–Vdovichenko method for calculating the critical temperature of the Ising model on Sierpiński carpets <span>(SC_k(a,b))</span>, originally introduced in <span>arxiv:1505.02699</span>. By reformulating the method in terms of purely real-valued transition matrices, we substantially reduce their dimension. This optimization, together with modern computational resources, enables us to reach generation <span>(k=10)</span> for the canonical <span>(SC_k(3,1))</span> carpet. Extrapolation from these data yields the most accurate estimate to date of the critical temperature <span>(T_c^{(3,1)} = 1.4782927(26))</span>. We further extend the analysis to additional members of the <span>(SC_k(a,b))</span> family and report their corresponding critical temperatures.</p>","PeriodicalId":787,"journal":{"name":"The European Physical Journal B","volume":"99 6","pages":""},"PeriodicalIF":1.9,"publicationDate":"2026-06-23","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://link.springer.com/content/pdf/10.1140/epjb/s10051-026-01196-1.pdf","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"148323237","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":"Nonlinear collective dynamics and Hamiltonian energy in time-delayed Morris–Lecar small-world networks","authors":"Lixiang Wei,&nbsp;Dong Li,&nbsp;Jiangang Zhang","doi":"10.1140/epjb/s10051-026-01173-8","DOIUrl":"10.1140/epjb/s10051-026-01173-8","url":null,"abstract":"<p>The collective dynamics of biological neural systems are profoundly influenced by the interplay between nonlinearity and network topology. In this study, a time-delayed bilayer neuronal network model is developed to investigate the mechanisms underlying synchronization and dynamic transitions. The network is constructed using Morris–Lecar (M–L) neurons within a small-world topology, incorporating electrical, chemical, and field coupling to replicate the complex feedback mechanism in neural information processing. Synchronization stability is rigorously evaluated using the master stability function, and the system’s Hamiltonian energy function is derived based on the Helmholtz theorem. Bifurcation analysis, Lyapunov exponents, and time series inspection reveal a rich repertoire of nonlinear dynamical modes induced by varying coupling parameters, including transitions from periodic spiking to chaotic bursting. Specifically, numerical simulations illustrate that the interplay of coupling strength and time delay drives the system through distinct dynamical regimes—ranging from asynchrony and chimera states to complete synchronization. Moreover, the results indicate that hybrid coupling mechanisms can effectively modulate the energy balance, suppressing chaos and enhancing global synchrony. This work not only elucidates the specific regulatory roles of delay and field effects but also contributes to the broader theoretical understanding of nonlinear dynamics in complex networks, providing references for designing efficient bio-inspired systems.</p>","PeriodicalId":787,"journal":{"name":"The European Physical Journal B","volume":"99 6","pages":""},"PeriodicalIF":1.9,"publicationDate":"2026-06-21","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"148323153","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":"Calculation of the T–n (n-carbon) phase diagram for the thienyl derivatives (PIR4 + PIR5) by the Landau phenomenological model","authors":"H. Yurtseven,&nbsp;O. Tari","doi":"10.1140/epjb/s10051-026-01191-6","DOIUrl":"10.1140/epjb/s10051-026-01191-6","url":null,"abstract":"<div><p>This study gives the calculation of the T–n phase diagram for the smectic–hexatic phase transitions in the binary mixture PIR4 + PIR5. By expanding the free energy in terms of the order parameters of the phases considered with the biquadratic coupling in the Landau phenomenological model, the phase line equations are obtained and they are fitted to the observed data in the literature. The Landau coefficients in the free energy expansion are associated with the temperature and concentration (C atoms) for the first-order transitions with the two triple points in this binary mixture. Our results indicate that the Landau model can explain the observed T–n phase diagram adequately and can be applied to some other binary mixtures.</p><h3>Graphical abstract</h3><div><figure><div><div><picture><img></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":1.9,"publicationDate":"2026-06-18","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"148281858","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":"Theory of coexisting superconductivity and excitonic pairing in a doped double-layer system under external bias","authors":"V. Apinyan,&nbsp;M. Sahakyan","doi":"10.1140/epjb/s10051-026-01192-5","DOIUrl":"10.1140/epjb/s10051-026-01192-5","url":null,"abstract":"<p>We study a double-layer square-lattice system with intralayer electron–-phonon coupling. Superconducting and excitonic pairings, as well as their coexistence, are examined as functions of key physical parameters, including temperature, intralayer and interlayer Coulomb interactions, electron–phonon coupling strength, doping, and the applied electric field. Superconductivity is shown to emerge from the coupling of intralayer phonons with the total charge density in the layers, resulting in a modification of the total electronic energy of the system. These results provide new insights into the possible mechanism of superconductivity in high-T<span>(_{C})</span> cuprate superconductors.</p>","PeriodicalId":787,"journal":{"name":"The European Physical Journal B","volume":"99 6","pages":""},"PeriodicalIF":1.9,"publicationDate":"2026-06-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"148281118","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}